z71vortec

i currently have a set of lpp longtubes with 3 inch ORY into a 3 inch single exhaust and out through a borla xr1... is this enough flow to support a maggie supercharger, cam, and overall goal of about 500+ horse? or do i need to go true dual? or upgrade to 4 inch?

gamble686

iTrader: (3)

You will begin to benefit from a more free flowing exhaust around that kind of power. The headers are fine as is, but a single 3.5"-4" or true dual 2 3/4" depending on your muffler would be a good choice. Single 3" is good to about 400 from my understanding beyond that it starts to restrict some.

06Sierra2

Im wondering the same thing. ive read about 3in-400hp before too. im wondering how much just adding a cutout helps with flow?

z71vortec

ok if i have to go true dual then ill be done with it and go true dual 3 inch with 2 borla proxs and an x pipe before them... so i ask... is there anywhere i can just pick up the rear tailpipes? everyone around here wants to rake my body over hot coals and sell my daughter to do a true dual setup in stainless... so i figure im a welder and fabricator... this is cake... however i cant bend pipes and dont feel like dickin around with u bends for 45 million weld joints... so can i just pick up some prebent tails from anywhere? its for an 05 avalanche.

budhayes3

iTrader: (19)

Is that 400 at the flywheel or rear wheels?

I'm wondering the same thing, as my exhaust is pretty much perfect for my current setup (mild 5.3, StainlessWorks LT's w/ 1 3/4" primaries, 2.5" collectors, and 2.5" to 3" y-pipe, with a 3" cutout after the y, and 3" I/O 18" Magnaflow, dumped after the axle), but I fear that it will choke my LQ9 which I'm planning to have about 475-500 crank hp (if I can ever afford to build it). I'm kinda crossing my fingers that the cutout will be helpful in this situation...

terravast4

iTrader: (25)

you can buy some pre-bent pipes from jegs....i bought a kit and handed it over to my welder.

mhotrodscooter

iTrader: (13)

I've got dual 3" single DI/DO magnaflow, and it was still holding me back 1mph & tenth or so. Not really sure cuz it wouldn't hook after that.

I think cam design plays a big role in exhaust setups

06Sierra2

yeah im sure cam design def plays a big role. i guess if swapping in a bigger motor the best route is to get a custom spec'd cam heavier on the exhaust side of course

TIM Z

iTrader: (12)

Yes, your exhaust will support over 500.

I dynoed with ebay stainless headers/ORY , 3'' into a shitty SI DO summit 3'' muffler and made 562 rwhp on a 90* day.

On the way home from the dyno i blew the back out of the muffler, so i put a maganaflow 3'' SI DO muffler on and i could feel the difference, wish i had it on the dyno pulls.

Was my setup optimal ? prob not, but it did support over 500 like you want to do.

ltr450ryder

iTrader: (13)

ya im wondering this to witht he 383 im building have lots of cr and a custom cam etc and didnt know if i should still with my 3in si/do or just do dual 3in and whatever mufflers but ya tim if u put the down i mit stay with the 3in si/do