🔧 Technical LS 6.0 3" or 2.5" exhaust?

[Shawn1112]

Didnt want this to get clogged up in my 71 build thread. I have to order my mufflers (super 40's) asap. Asking you LS experts what would you do, 3" or 2.5"?
MY headers at the collectors are 3" and I can run a 3" exhaust dumping it pre-axle. Would cost me a little more money, which isnt the issue as its not that much more.
I guess my issue is, will there be that much of a difference if I drop down to a 2.5"? SC or turbo probably in the future (next year)

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[daturbosix]

Great White Drake

 

[NOMIEZVR4]

I'd do 3'

 

[Bob Kazamakis]

I’m in a similar boat and I think I’m going to go 2.5”. Dual 2.5 flows nearly 10 sq.in and a 3” single flows 7.1 so if you go turbo and can fit a 4” downpipe I’d go dual 3”. If you can only fit a 3-3.5” than dual 2.5” will support that flow just fine.

Weight and packaging of a dual 3” doesn’t seem worth the hassle personally. I do plan on full tail pipes to keep it a bit quieter and probably run a loud valve when I want it rowdy sounding.

 

[1quick]

I think 3” sounds better myself, performance wise probably not much of a difference until your in the 1000hp range

 

[Bob Kazamakis]

Variable Exhaust Solutions

Boost and Vacuum Actuated Exhaust Cutouts/Dump, Turbo Accessories, fender exit, hood exit, electric cutout,

loudvalves.com

 

[Shawn1112]

I talked with Jeremy at Satera as he will be doing my turbo if thats the route I go next year. He suggested 2.5", so pretty sure thats the way I'm going to go.

 

[dun4791]

I think 3” sounds better myself, performance wise probably not much of a difference until your in the 1000hp range

I always thought less than 500hp go 2.5, over 500hp 3”
?‍
But the sound, yes 3 is way better

 

[Bob Kazamakis]

I talked with Jeremy at Satera as he will be doing my turbo if thats the route I go next year. He suggested 2.5", so pretty sure thats the way I'm going to go.

IceCreamAssassin has a boost activated loud valve he can chime in.

 

[LikeABauce302]

If you're going with a turbo in the future, just do whatever is the cheaper option. You probably won't reuse any of your exhaust parts when the turbo kit is fabbed.

 

[Gav'sPurpleZ]

2.5"

 

[IceCreamAssassin]

My dp is 3” and goes to two 2 1/2”... before the split it does have a 3” loudvalve that starts to dump and 3psi. I’m super happy with how it all sounds and performs.

 

[Jon01]

If you're going to go for over 700 wheel once you add boost I'd say 3in. Under 2.5".

Edit - are you going to use the same exhaust once you add boost or build new stuff?

 

[Shawn1112]

If you're going to go for over 700 wheel once you add boost I'd say 3in. Under 2.5".

Edit - are you going to use the same exhaust once you add boost or build new stuff?

I'm thinking if I go supercharger exhaust will stay the same. If turbo, then it will get all new.
The plan is turbo unless I see a SC at a steal, then I'll jump on it

 

[Bob Kazamakis]

I’d do an X pipe and then if you go turbo, just merge the downpipe into that connection and keep most of the exhaust you already invested in.

 

[Jon01]

I'm thinking if I go supercharger exhaust will stay the same. If turbo, then it will get all new.
The plan is turbo unless I see a SC at a steal, then I'll jump on it

Right on, in that case carry on.
If or when you do go turbo keep in mind that chambered mufflers cost a turbo car significant power.

 

[Bob Kazamakis]

Not with a dump valve

 

[Shawn1112]

Not with a dump valve

Ah, makes sense

 

[Great White Drake]

If doing turbo next year, save your money this year and do 2.5 because it’ll have a whole different exhaust anyway when you go turbo. If doing a sc, I’d go 3” and wouldn’t use those flownasters anyway.

 

[Great White Drake]

I'm thinking if I go supercharger exhaust will stay the same. If turbo, then it will get all new.
The plan is turbo unless I see a SC at a steal, then I'll jump on it

Good plan, just seen this.

 

[Ron Vogel]

I’d do a step down. If you have 3” collectors, extend the 3” about 2 feet, step it down to 2.5”, and install a balance pipe right after the transition. This will give you best of both worlds.

 

[CMNTMXR57]

2.5 IMO also. Another thing, I personally don't think Flowmaster's sound good on an LS motor. On an Big Block. Different story. Old school small block, yep. But the LS motor just doesn't sound right with them.