NovaKid

I have a stock LS6 with some bolt ons and I'm guessing it will be putting out around 450-470 hp. I'm trying to finish up my install and my existing exhaust is 2.5 inch from my old gen I engine. Should I pony up the cash and put in 3 inch exhaust? Will the 2.5 inch be too restrictive? What do you guys think and why?

Latch

iTrader: (8)

You mean a single 2.5" exhaust or dual 2.5"? If it's a single exhaust then holy **** yes that will be restrictive. That's smaller than the stock exhaust on an LS1. Dual 2.5" is more than enough for power levels under 500 or so.

NovaKid

Hahaha! Yeah, definitely dual... Thanks Latch, had a good laugh on that one.

JWStevens

iTrader: (1)

As long as you don't have flowmasters! It seems like every car I take them off of picks up.

NovaKid

Really? The funny thing is I do have 40 series flowmasters... damn, they gotta be 10 years old though. That's another reason I was debating on new exhaust. Sounded good when I parked the beast

JWStevens

iTrader: (1)

Def don't take my word for it! Its just always worked out like that for me.

NovaKid

Oh I'm not, I just like to see what everyone says and then look for a collective opinion.

JWStevens

iTrader: (1)

I've been hung up on dynomax ultraflows the last 5 or so years.

Blk98Vert

iTrader: (2)

Try swapping them for magnaflow 4x9s they are straight through rather than chambered like the flowmaster. Also sweet thunders would sound great

NovaKid

I'll have to check those out, I definitely don't want something quiet. Thanks for the suggestions guys..

Anyone else? Looks like the money I save on keeping the 2.5" exhaust may be going toward mufflers eventually

01M6TA

iTrader: (1)

i have 2.5 true duals with no problems. i only have a few bolt ons though.

butler

How fast are you going? 3" worked the best for me. Anything less backed the motor up. Backpressure is not good I do not care what anyone says. Bullit mufflers never hurt my times but a full exhaust added 3/10's.

BOBS99SS

iTrader: (2)

i like flowmasters, honest some of there stuff sounds great, on a dual set up i dont think swapin the flowmasters out will gain you anything, imo i have duals with sweet thunders and i love them , loud and sound great,i think the chambered style sounds best on the ls motors

speedtigger

iTrader: (16)

I am pretty sure you will pick up some going to 3" at 450 whp. How much depends on how good what you have is vs what you replace it with.

NovaKid

I don't exactly know how much *** I'll be haulin'? I'm just getting to the end stages of my ls6/nova install.

I'm guessing it will be around 450 at the flywheel with all the smog BS taken off, long tube headers/full exhaust, dyno tuned, cold air intake. Not sure though. I just stared getting into the LS scene after my old 350 went south a year ago

wysemunky

iTrader: (2)

I could see 2.5" crush bent exhaust being a restriction. You would probably pick up more going to mandrel bent pipe and either and X crossover or an H if you don't have room, then by switching mufflers. If you want new mufflers too the Magnaflow 4x9's are definitely quieter then flowmaster 40's, atleast at idle and cruise speeds.

lees02WS6

iTrader: (5)

https://ls1tech.com/forums/generatio...aust-info.html

bww3588

iTrader: (49)

2.5's will be fine. Most people go straight for 3 inch dual's for room to grow. If you already have 2.5's, don't waste your money until you actually need them.

TooManySS's

There was a site years back that had flow numbers for all popular mufflers.
The whole flowmaster line at best beat stock mufflers by 15% better flow numbers, but they we less than louvered cherry bomb types.
The best were race bullets, ultra flow type mufflers followed by the rest which all flow double a stock one which average 180 CFM.

The problem with blowmaster is shown right in there advertising.
Redirecting exhaust gases to use sound to cancel sound.
Everything your taught about exhaust says the straightest path is the best.
The smoother the turns the better and so on.
Kinda goes against it doesn't it.
Some people say its sounds cool and I can tell a flowmaster system from quite a distance, it has a echo tin sound like no other! Its sounds fake!

NovaKid

Trying to get an idea of what they sound like... I figure I'll do a cam down the road, but not for a while.

http://www.youtube.com/watch?v=Q851F8GVe78

http://www.youtube.com/watch?v=31Mk7LyQzac

http://www.youtube.com/watch?v=a-BL891mGHY