Quietest side pipe muffler insert
Thread Starter
Advanced
Joined: Aug 2006
Posts: 75
Likes: 28
Quietest side pipe muffler insert
I realize this topic has been beat to death.
Building a mostly stock 70 LT-1 coupe. Original engine, trans and rear. Engine will be built to stock almost specs with a little tighter quench. I have access to 100LL so detonation isn't an issue.
Only using two "day two" mods that can be easily "undone" if I ever want to go back 100% stock.
1. Koni adjustable shocks.
2. Kustom headers and side pipes. These are the ones sold by GM which have GM part numbers stamped on them.
I am old. As much as I love the side pipes, I want them as quiet as possible.
Preliminary research indicates that the Hooker reverse flow, part number 21021HKR is the best I can hope for.
https://www.jegs.com/i/Hooker/520/21...UaApRbEALw_wcB
Am I on the right track?
Building a mostly stock 70 LT-1 coupe. Original engine, trans and rear. Engine will be built to stock almost specs with a little tighter quench. I have access to 100LL so detonation isn't an issue.
Only using two "day two" mods that can be easily "undone" if I ever want to go back 100% stock.
1. Koni adjustable shocks.
2. Kustom headers and side pipes. These are the ones sold by GM which have GM part numbers stamped on them.
I am old. As much as I love the side pipes, I want them as quiet as possible.
Preliminary research indicates that the Hooker reverse flow, part number 21021HKR is the best I can hope for.
https://www.jegs.com/i/Hooker/520/21...UaApRbEALw_wcB
Am I on the right track?
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,502
From: Little Rock AR
I'm building an LT-1 for mine right now. I have the Vettepacks in my side pipes. Should be finished in a few weeks. Not quiet but not too bad.
The Hooker reverse flows should be the quietest inserts. LT -1 cam has a lot of exhaust duration and runs pretty well even with exhaust restriction. Keeping the overlap in check helps with restrictive exhaust. Most tight LCA aftermarket cams will get strangled to death with restrictive exhaust. LT-1 is VERY wide 116 LCA.
The Hooker reverse flows should be the quietest inserts. LT -1 cam has a lot of exhaust duration and runs pretty well even with exhaust restriction. Keeping the overlap in check helps with restrictive exhaust. Most tight LCA aftermarket cams will get strangled to death with restrictive exhaust. LT-1 is VERY wide 116 LCA.
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Do you have part numbers for the rest of the system, or a picture?
The Hooker-style sidepipes (or Dougs, or several others), put a 4" pipe down the side, with the collector outside the frame.
The 1969, only, stock GM sidepipes do something else, and I didn't think they accepted a 4" pipe insert. But they do fit under the stock sidepipe covers.
It sounds like you have some hybrid system, with a GM part number somewhere?
The Hooker-style sidepipes (or Dougs, or several others), put a 4" pipe down the side, with the collector outside the frame.
The 1969, only, stock GM sidepipes do something else, and I didn't think they accepted a 4" pipe insert. But they do fit under the stock sidepipe covers.
It sounds like you have some hybrid system, with a GM part number somewhere?
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Do you have part numbers for the rest of the system, or a picture?
The Hooker-style sidepipes (or Dougs, or several others), put a 4" pipe down the side, with the collector outside the frame.
The 1969, only, stock GM sidepipes do something else, and I didn't think they accepted a 4" pipe insert. But they do fit under the stock sidepipe covers.
It sounds like you have some hybrid system, with a GM part number somewhere?
The Hooker-style sidepipes (or Dougs, or several others), put a 4" pipe down the side, with the collector outside the frame.
The 1969, only, stock GM sidepipes do something else, and I didn't think they accepted a 4" pipe insert. But they do fit under the stock sidepipe covers.
It sounds like you have some hybrid system, with a GM part number somewhere?
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Thanks @Richard454! I'm curious to see how the OP will get those to fit on an LT-1 SBC. Those are for an L88 BBC.
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Thanks @Richard454! I'm curious to see how the OP will get those to fit on an LT-1 SBC. Those are for an L88 BBC.
They both use the same side tube-3960713 - Side Tube
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
The first hit on that part number was this thread, with catalog pages, and other info. Very nifty!
https://www.yenko.net/forum/showthread.php?t=177523
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,502
From: Little Rock AR
Kustom made them for GM. Might have been one other supplier also. They were for road racing. Shown in the Chevy Power Manual.
Your link above is for the louder glass packs. You want the quieter "reverse flow" inserts.
https://www.jegs.com/i/Hooker-Header...21002/10002/-1
Your link above is for the louder glass packs. You want the quieter "reverse flow" inserts.
https://www.jegs.com/i/Hooker-Header...21002/10002/-1
Last edited by stingr69; Apr 7, 2024 at 10:14 PM.
Drifting
Joined: Nov 2007
Posts: 1,716
Likes: 279
From: New York
Drifting
Joined: Jul 2005
Posts: 1,623
Likes: 29
From: The Netherlands
Le Mans Master
Joined: May 2007
Posts: 5,025
Likes: 1,120
From: North tonawanda NY
Kustom made them for GM. Might have been one other supplier also. They were for road racing. Shown in the Chevy Power Manual.
Your link above is for the louder glass packs. You want the quieter "reverse flow" inserts.
https://www.jegs.com/i/Hooker-Header...21002/10002/-1
Your link above is for the louder glass packs. You want the quieter "reverse flow" inserts.
https://www.jegs.com/i/Hooker-Header...21002/10002/-1
I have gone from sweet thunder inserts to american chambered myself and I find the classic chamber vette packs doesnt have as much drone and just a bit more pleasing sounding but they are still not quiet.
Last edited by augiedoggy; Apr 8, 2024 at 10:19 PM.
Thread Starter
Advanced
Joined: Aug 2006
Posts: 75
Likes: 28
Ah, that makes sense. I didn't realize those existed. Those are basically the Hooker or Doug's style sidepipes.
The first hit on that part number was this thread, with catalog pages, and other info. Very nifty!
https://www.yenko.net/forum/showthread.php?t=177523
The first hit on that part number was this thread, with catalog pages, and other info. Very nifty!
https://www.yenko.net/forum/showthread.php?t=177523
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Were these the same sidepipe headers (along with the L88 versions) that the first batch of C3 racers were using in 68? I couldn't find them in my 1980 Chassis and Body Parts catalog, but perhaps race parts were kept out of that.
I'm looking forward to seeing the completed project!
Thread Starter
Advanced
Joined: Aug 2006
Posts: 75
Likes: 28
I am running an LT-1 spec engine in my 69 Z/28 right now. It is coded as an L46, but I installed an LT-1 camshaft, and used the Z high rise and carb, which is very similar to the 70 intake and carb. Yes, I know the numbers aren't the same, but performance is. On that set up, I am running headers with a 2.5 inch Magnaflow set up. I have the original 302 complete with smog, but put this engine in "temporarily" in 2012. It is so much fun, I can't talk myself into taking it back stock; especially with the manifolds and smog set up.
Even though the Corvette has the original engine, trans and rear, it is missing the smog set up. I figured the Kustom side pipes would be the ultimate day two... and a lot more fun. Not like this is going to be a daily driver. But I will drive it.
Even though the Corvette has the original engine, trans and rear, it is missing the smog set up. I figured the Kustom side pipes would be the ultimate day two... and a lot more fun. Not like this is going to be a daily driver. But I will drive it.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,502
From: Little Rock AR
Lynnbilodeau,
I have a stroker 383/TKX in the Vette right now but the original L-82 short block is getting back dated to '70 LT-1 heads and an LT-1 cam before being reinstalled. The '80 hood will never accommodate the LT-1 intake so I am keeping the stock aluminum intake and Larsburetor. The sidepipes are Doug's.
My '69 Z/28 still has the 302 with full smog dress but I run a bigger Crane cam. Plans for that one involve an overhaul and a smaller Isky solid flat tappet cam. Might put the Hooker super comps back on while Im at it. Should run fairly well through the repro chambered exhaust.
I have a stroker 383/TKX in the Vette right now but the original L-82 short block is getting back dated to '70 LT-1 heads and an LT-1 cam before being reinstalled. The '80 hood will never accommodate the LT-1 intake so I am keeping the stock aluminum intake and Larsburetor. The sidepipes are Doug's.
My '69 Z/28 still has the 302 with full smog dress but I run a bigger Crane cam. Plans for that one involve an overhaul and a smaller Isky solid flat tappet cam. Might put the Hooker super comps back on while Im at it. Should run fairly well through the repro chambered exhaust.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,502
From: Little Rock AR
Those are really neat, and a great fit for an otherwise original LT-1.
Were these the same sidepipe headers (along with the L88 versions) that the first batch of C3 racers were using in 68? I couldn't find them in my 1980 Chassis and Body Parts catalog, but perhaps race parts were kept out of that.
I'm looking forward to seeing the completed project!
Were these the same sidepipe headers (along with the L88 versions) that the first batch of C3 racers were using in 68? I couldn't find them in my 1980 Chassis and Body Parts catalog, but perhaps race parts were kept out of that.
I'm looking forward to seeing the completed project!