diff --git a/beacon_node/lighthouse_network/src/config.rs b/beacon_node/lighthouse_network/src/config.rs
index 6bb64f83f..789242e8d 100644
--- a/beacon_node/lighthouse_network/src/config.rs
+++ b/beacon_node/lighthouse_network/src/config.rs
@@ -16,8 +16,10 @@ use std::sync::Arc;
 use std::time::Duration;
 use types::{ForkContext, ForkName};
 
-/// The maximum transmit size of gossip messages in bytes.
-pub const GOSSIP_MAX_SIZE: usize = 10 * 1_048_576; // 10M
+/// The maximum transmit size of gossip messages in bytes pre-merge.
+const GOSSIP_MAX_SIZE: usize = 1_048_576; // 1M
+/// The maximum transmit size of gossip messages in bytes post-merge.
+const GOSSIP_MAX_SIZE_POST_MERGE: usize = 10 * 1_048_576; // 10M
 /// This is a constant to be used in discovery. The lower bound of the gossipsub mesh.
 pub const MESH_N_LOW: usize = 6;
 
@@ -40,6 +42,15 @@ pub const DUPLICATE_CACHE_TIME: Duration = Duration::from_secs(33 * 12 + 1);
 // const MESSAGE_DOMAIN_INVALID_SNAPPY: [u8; 4] = [0, 0, 0, 0];
 const MESSAGE_DOMAIN_VALID_SNAPPY: [u8; 4] = [1, 0, 0, 0];
 
+/// The maximum size of gossip messages.
+pub fn gossip_max_size(is_merge_enabled: bool) -> usize {
+    if is_merge_enabled {
+        GOSSIP_MAX_SIZE_POST_MERGE
+    } else {
+        GOSSIP_MAX_SIZE
+    }
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize)]
 #[serde(default)]
 /// Network configuration for lighthouse.
@@ -231,6 +242,7 @@ pub fn gossipsub_config(fork_context: Arc<ForkContext>) -> GossipsubConfig {
         }
     }
 
+    let is_merge_enabled = fork_context.fork_exists(ForkName::Merge);
     let gossip_message_id = move |message: &GossipsubMessage| {
         MessageId::from(
             &Sha256::digest(
@@ -239,7 +251,7 @@ pub fn gossipsub_config(fork_context: Arc<ForkContext>) -> GossipsubConfig {
         )
     };
     GossipsubConfigBuilder::default()
-        .max_transmit_size(GOSSIP_MAX_SIZE)
+        .max_transmit_size(gossip_max_size(is_merge_enabled))
         .heartbeat_interval(Duration::from_millis(700))
         .mesh_n(8)
         .mesh_n_low(MESH_N_LOW)
diff --git a/beacon_node/lighthouse_network/src/lib.rs b/beacon_node/lighthouse_network/src/lib.rs
index b37b69dcf..058b38ceb 100644
--- a/beacon_node/lighthouse_network/src/lib.rs
+++ b/beacon_node/lighthouse_network/src/lib.rs
@@ -16,7 +16,7 @@ pub mod rpc;
 mod service;
 pub mod types;
 
-pub use config::GOSSIP_MAX_SIZE;
+pub use config::gossip_max_size;
 
 use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
 use std::str::FromStr;
diff --git a/beacon_node/lighthouse_network/src/rpc/codec/ssz_snappy.rs b/beacon_node/lighthouse_network/src/rpc/codec/ssz_snappy.rs
index f5d7232a6..0924dca0c 100644
--- a/beacon_node/lighthouse_network/src/rpc/codec/ssz_snappy.rs
+++ b/beacon_node/lighthouse_network/src/rpc/codec/ssz_snappy.rs
@@ -697,9 +697,9 @@ mod tests {
         version: Version,
         message: &mut BytesMut,
     ) -> Result<Option<RPCResponse<Spec>>, RPCError> {
-        let max_packet_size = 1_048_576;
         let snappy_protocol_id = ProtocolId::new(protocol, version, Encoding::SSZSnappy);
         let fork_context = Arc::new(fork_context());
+        let max_packet_size = max_rpc_size(&fork_context);
         let mut snappy_outbound_codec =
             SSZSnappyOutboundCodec::<Spec>::new(snappy_protocol_id, max_packet_size, fork_context);
         // decode message just as snappy message
@@ -1124,7 +1124,7 @@ mod tests {
         );
     }
 
-    /// Test sending a message with encoded length prefix > MAX_RPC_SIZE.
+    /// Test sending a message with encoded length prefix > max_rpc_size.
     #[test]
     fn test_decode_invalid_length() {
         // 10 byte snappy stream identifier
diff --git a/beacon_node/lighthouse_network/src/rpc/handler.rs b/beacon_node/lighthouse_network/src/rpc/handler.rs
index 1a12c2600..37724e028 100644
--- a/beacon_node/lighthouse_network/src/rpc/handler.rs
+++ b/beacon_node/lighthouse_network/src/rpc/handler.rs
@@ -5,7 +5,7 @@ use super::methods::{
     GoodbyeReason, RPCCodedResponse, RPCResponseErrorCode, RequestId, ResponseTermination,
 };
 use super::outbound::OutboundRequestContainer;
-use super::protocol::{InboundRequest, Protocol, RPCError, RPCProtocol};
+use super::protocol::{max_rpc_size, InboundRequest, Protocol, RPCError, RPCProtocol};
 use super::{RPCReceived, RPCSend};
 use crate::rpc::outbound::{OutboundFramed, OutboundRequest};
 use crate::rpc::protocol::InboundFramed;
@@ -951,6 +951,7 @@ where
                     OutboundRequestContainer {
                         req: req.clone(),
                         fork_context: self.fork_context.clone(),
+                        max_rpc_size: max_rpc_size(&self.fork_context),
                     },
                     (),
                 )
diff --git a/beacon_node/lighthouse_network/src/rpc/mod.rs b/beacon_node/lighthouse_network/src/rpc/mod.rs
index c7bfd405d..ebd624061 100644
--- a/beacon_node/lighthouse_network/src/rpc/mod.rs
+++ b/beacon_node/lighthouse_network/src/rpc/mod.rs
@@ -30,7 +30,7 @@ pub use methods::{
     RPCResponseErrorCode, RequestId, ResponseTermination, StatusMessage, MAX_REQUEST_BLOCKS,
 };
 pub(crate) use outbound::OutboundRequest;
-pub use protocol::{Protocol, RPCError, MAX_RPC_SIZE};
+pub use protocol::{max_rpc_size, Protocol, RPCError};
 
 pub(crate) mod codec;
 mod handler;
@@ -186,6 +186,7 @@ where
             SubstreamProtocol::new(
                 RPCProtocol {
                     fork_context: self.fork_context.clone(),
+                    max_rpc_size: max_rpc_size(&self.fork_context),
                     phantom: PhantomData,
                 },
                 (),
diff --git a/beacon_node/lighthouse_network/src/rpc/outbound.rs b/beacon_node/lighthouse_network/src/rpc/outbound.rs
index 1c908887e..17201c6cf 100644
--- a/beacon_node/lighthouse_network/src/rpc/outbound.rs
+++ b/beacon_node/lighthouse_network/src/rpc/outbound.rs
@@ -2,7 +2,7 @@ use std::marker::PhantomData;
 
 use super::methods::*;
 use super::protocol::Protocol;
-use super::protocol::{ProtocolId, MAX_RPC_SIZE};
+use super::protocol::ProtocolId;
 use super::RPCError;
 use crate::rpc::protocol::Encoding;
 use crate::rpc::protocol::Version;
@@ -29,6 +29,7 @@ use types::{EthSpec, ForkContext};
 pub struct OutboundRequestContainer<TSpec: EthSpec> {
     pub req: OutboundRequest<TSpec>,
     pub fork_context: Arc<ForkContext>,
+    pub max_rpc_size: usize,
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -150,7 +151,7 @@ where
             Encoding::SSZSnappy => {
                 let ssz_snappy_codec = BaseOutboundCodec::new(SSZSnappyOutboundCodec::new(
                     protocol,
-                    MAX_RPC_SIZE,
+                    self.max_rpc_size,
                     self.fork_context.clone(),
                 ));
                 OutboundCodec::SSZSnappy(ssz_snappy_codec)
diff --git a/beacon_node/lighthouse_network/src/rpc/protocol.rs b/beacon_node/lighthouse_network/src/rpc/protocol.rs
index a6a015878..1e6504199 100644
--- a/beacon_node/lighthouse_network/src/rpc/protocol.rs
+++ b/beacon_node/lighthouse_network/src/rpc/protocol.rs
@@ -22,7 +22,7 @@ use tokio_util::{
 };
 use types::{
     BeaconBlock, BeaconBlockAltair, BeaconBlockBase, BeaconBlockMerge, EthSpec, ForkContext,
-    Hash256, MainnetEthSpec, Signature, SignedBeaconBlock,
+    ForkName, Hash256, MainnetEthSpec, Signature, SignedBeaconBlock,
 };
 
 lazy_static! {
@@ -92,8 +92,10 @@ lazy_static! {
 
 }
 
-/// The maximum bytes that can be sent across the RPC.
-pub const MAX_RPC_SIZE: usize = 10 * 1_048_576; // 10M
+/// The maximum bytes that can be sent across the RPC pre-merge.
+pub(crate) const MAX_RPC_SIZE: usize = 1_048_576; // 1M
+/// The maximum bytes that can be sent across the RPC post-merge.
+pub(crate) const MAX_RPC_SIZE_POST_MERGE: usize = 10 * 1_048_576; // 10M
 /// The protocol prefix the RPC protocol id.
 const PROTOCOL_PREFIX: &str = "/eth2/beacon_chain/req";
 /// Time allowed for the first byte of a request to arrive before we time out (Time To First Byte).
@@ -102,6 +104,15 @@ const TTFB_TIMEOUT: u64 = 5;
 /// established before the stream is terminated.
 const REQUEST_TIMEOUT: u64 = 15;
 
+/// Returns the maximum bytes that can be sent across the RPC.
+pub fn max_rpc_size(fork_context: &ForkContext) -> usize {
+    if fork_context.fork_exists(ForkName::Merge) {
+        MAX_RPC_SIZE_POST_MERGE
+    } else {
+        MAX_RPC_SIZE
+    }
+}
+
 /// Protocol names to be used.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Protocol {
@@ -170,6 +181,7 @@ impl std::fmt::Display for Version {
 #[derive(Debug, Clone)]
 pub struct RPCProtocol<TSpec: EthSpec> {
     pub fork_context: Arc<ForkContext>,
+    pub max_rpc_size: usize,
     pub phantom: PhantomData<TSpec>,
 }
 
@@ -206,7 +218,7 @@ impl RpcLimits {
         Self { min, max }
     }
 
-    /// Returns true if the given length is greater than `MAX_RPC_SIZE` or out of
+    /// Returns true if the given length is greater than `max_rpc_size` or out of
     /// bounds for the given ssz type, returns false otherwise.
     pub fn is_out_of_bounds(&self, length: usize, max_rpc_size: usize) -> bool {
         length > std::cmp::min(self.max, max_rpc_size) || length < self.min
@@ -365,7 +377,7 @@ where
                 Encoding::SSZSnappy => {
                     let ssz_snappy_codec = BaseInboundCodec::new(SSZSnappyInboundCodec::new(
                         protocol,
-                        MAX_RPC_SIZE,
+                        self.max_rpc_size,
                         self.fork_context.clone(),
                     ));
                     InboundCodec::SSZSnappy(ssz_snappy_codec)
diff --git a/beacon_node/lighthouse_network/tests/common/mod.rs b/beacon_node/lighthouse_network/tests/common/mod.rs
index 6daaeb335..865946a22 100644
--- a/beacon_node/lighthouse_network/tests/common/mod.rs
+++ b/beacon_node/lighthouse_network/tests/common/mod.rs
@@ -17,7 +17,7 @@ type E = MinimalEthSpec;
 use tempfile::Builder as TempBuilder;
 
 /// Returns a dummy fork context
-fn fork_context() -> ForkContext {
+pub fn fork_context() -> ForkContext {
     let mut chain_spec = E::default_spec();
     // Set fork_epoch to `Some` to ensure that the `ForkContext` object
     // includes altair in the list of forks
diff --git a/beacon_node/lighthouse_network/tests/rpc_tests.rs b/beacon_node/lighthouse_network/tests/rpc_tests.rs
index 77d014e6a..b270765f8 100644
--- a/beacon_node/lighthouse_network/tests/rpc_tests.rs
+++ b/beacon_node/lighthouse_network/tests/rpc_tests.rs
@@ -1,7 +1,7 @@
 #![cfg(test)]
 use lighthouse_network::rpc::methods::*;
 use lighthouse_network::{
-    rpc::MAX_RPC_SIZE, BehaviourEvent, Libp2pEvent, ReportSource, Request, Response,
+    rpc::max_rpc_size, BehaviourEvent, Libp2pEvent, ReportSource, Request, Response,
 };
 use slog::{debug, warn, Level};
 use ssz::Encode;
@@ -11,16 +11,16 @@ use std::time::Duration;
 use tokio::runtime::Runtime;
 use tokio::time::sleep;
 use types::{
-    BeaconBlock, BeaconBlockAltair, BeaconBlockBase, BeaconBlockMerge, Epoch, EthSpec, Hash256,
-    MinimalEthSpec, Signature, SignedBeaconBlock, Slot,
+    BeaconBlock, BeaconBlockAltair, BeaconBlockBase, BeaconBlockMerge, Epoch, EthSpec, ForkContext,
+    Hash256, MinimalEthSpec, Signature, SignedBeaconBlock, Slot,
 };
 
 mod common;
 
 type E = MinimalEthSpec;
 
-/// Merge block with length < MAX_RPC_SIZE.
-fn merge_block_small() -> BeaconBlock<E> {
+/// Merge block with length < max_rpc_size.
+fn merge_block_small(fork_context: &ForkContext) -> BeaconBlock<E> {
     let mut block = BeaconBlockMerge::empty(&E::default_spec());
     let tx = VariableList::from(vec![0; 1024]);
     let txs = VariableList::from(std::iter::repeat(tx).take(100).collect::<Vec<_>>());
@@ -28,14 +28,14 @@ fn merge_block_small() -> BeaconBlock<E> {
     block.body.execution_payload.transactions = txs;
 
     let block = BeaconBlock::Merge(block);
-    assert!(block.ssz_bytes_len() <= MAX_RPC_SIZE);
+    assert!(block.ssz_bytes_len() <= max_rpc_size(fork_context));
     block
 }
 
 /// Merge block with length > MAX_RPC_SIZE.
 /// The max limit for a merge block is in the order of ~16GiB which wouldn't fit in memory.
 /// Hence, we generate a merge block just greater than `MAX_RPC_SIZE` to test rejection on the rpc layer.
-fn merge_block_large() -> BeaconBlock<E> {
+fn merge_block_large(fork_context: &ForkContext) -> BeaconBlock<E> {
     let mut block = BeaconBlockMerge::empty(&E::default_spec());
     let tx = VariableList::from(vec![0; 1024]);
     let txs = VariableList::from(std::iter::repeat(tx).take(100000).collect::<Vec<_>>());
@@ -43,7 +43,7 @@ fn merge_block_large() -> BeaconBlock<E> {
     block.body.execution_payload.transactions = txs;
 
     let block = BeaconBlock::Merge(block);
-    assert!(block.ssz_bytes_len() > MAX_RPC_SIZE);
+    assert!(block.ssz_bytes_len() > max_rpc_size(fork_context));
     block
 }
 
@@ -180,7 +180,7 @@ fn test_blocks_by_range_chunked_rpc() {
         let signed_full_block = SignedBeaconBlock::from_block(full_block, Signature::empty());
         let rpc_response_altair = Response::BlocksByRange(Some(Box::new(signed_full_block)));
 
-        let full_block = merge_block_small();
+        let full_block = merge_block_small(&common::fork_context());
         let signed_full_block = SignedBeaconBlock::from_block(full_block, Signature::empty());
         let rpc_response_merge_small = Response::BlocksByRange(Some(Box::new(signed_full_block)));
 
@@ -309,7 +309,7 @@ fn test_blocks_by_range_over_limit() {
         });
 
         // BlocksByRange Response
-        let full_block = merge_block_large();
+        let full_block = merge_block_large(&common::fork_context());
         let signed_full_block = SignedBeaconBlock::from_block(full_block, Signature::empty());
         let rpc_response_merge_large = Response::BlocksByRange(Some(Box::new(signed_full_block)));
 
@@ -666,7 +666,7 @@ fn test_blocks_by_root_chunked_rpc() {
         let signed_full_block = SignedBeaconBlock::from_block(full_block, Signature::empty());
         let rpc_response_altair = Response::BlocksByRoot(Some(Box::new(signed_full_block)));
 
-        let full_block = merge_block_small();
+        let full_block = merge_block_small(&common::fork_context());
         let signed_full_block = SignedBeaconBlock::from_block(full_block, Signature::empty());
         let rpc_response_merge_small = Response::BlocksByRoot(Some(Box::new(signed_full_block)));
 
diff --git a/beacon_node/src/config.rs b/beacon_node/src/config.rs
index 37963cd58..ab51c218b 100644
--- a/beacon_node/src/config.rs
+++ b/beacon_node/src/config.rs
@@ -468,7 +468,8 @@ pub fn get_config<E: EthSpec>(
         };
     }
 
-    client_config.chain.max_network_size = lighthouse_network::GOSSIP_MAX_SIZE;
+    client_config.chain.max_network_size =
+        lighthouse_network::gossip_max_size(spec.merge_fork_epoch.is_some());
 
     if cli_args.is_present("slasher") {
         let slasher_dir = if let Some(slasher_dir) = cli_args.value_of("slasher-dir") {
diff --git a/consensus/types/src/execution_payload.rs b/consensus/types/src/execution_payload.rs
index e1f7a045b..0080b092c 100644
--- a/consensus/types/src/execution_payload.rs
+++ b/consensus/types/src/execution_payload.rs
@@ -1,5 +1,4 @@
 use crate::{test_utils::TestRandom, *};
-use safe_arith::{ArithError, SafeArith};
 use serde_derive::{Deserialize, Serialize};
 use ssz::Encode;
 use ssz_derive::{Decode, Encode};
@@ -44,19 +43,6 @@ impl<T: EthSpec> ExecutionPayload<T> {
         Self::default()
     }
 
-    /// Returns the ssz size of `self`.
-    pub fn payload_size(&self) -> Result<usize, ArithError> {
-        let mut tx_size = ssz::BYTES_PER_LENGTH_OFFSET.safe_mul(self.transactions.len())?;
-        for tx in self.transactions.iter() {
-            tx_size.safe_add_assign(tx.len())?;
-        }
-        Self::empty()
-            .as_ssz_bytes()
-            .len()
-            .safe_add(<u8 as Encode>::ssz_fixed_len().safe_mul(self.extra_data.len())?)?
-            .safe_add(tx_size)
-    }
-
     #[allow(clippy::integer_arithmetic)]
     /// Returns the maximum size of an execution payload.
     pub fn max_execution_payload_size() -> usize {
@@ -68,26 +54,3 @@ impl<T: EthSpec> ExecutionPayload<T> {
         + (T::max_transactions_per_payload() * (ssz::BYTES_PER_LENGTH_OFFSET + T::max_bytes_per_transaction()))
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_payload_size() {
-        let mut payload = ExecutionPayload::<crate::MainnetEthSpec>::empty();
-
-        assert_eq!(
-            payload.as_ssz_bytes().len(),
-            payload.payload_size().unwrap()
-        );
-
-        payload.extra_data = VariableList::from(vec![42; 16]);
-        payload.transactions = VariableList::from(vec![VariableList::from(vec![42; 42])]);
-
-        assert_eq!(
-            payload.as_ssz_bytes().len(),
-            payload.payload_size().unwrap()
-        );
-    }
-}
diff --git a/lighthouse/src/main.rs b/lighthouse/src/main.rs
index 75447d35a..693b3de82 100644
--- a/lighthouse/src/main.rs
+++ b/lighthouse/src/main.rs
@@ -367,7 +367,7 @@ fn run<E: EthSpec>(
     let logfile_compress = matches.is_present("logfile-compress");
 
     // Construct the path to the log file.
-    let mut log_path: Option<PathBuf> = parse_optional(matches, "logfile")?;
+    let mut log_path: Option<PathBuf> = clap_utils::parse_optional(matches, "logfile")?;
     if log_path.is_none() {
         log_path = match matches.subcommand_name() {
             Some("beacon_node") => Some(