1Legged60ftHnter

I have a hooker catback on my car currently and was planning on re-using it until last night a friend and I were talking. He said he thought it might cause a restriction. It is 3" diameter to the muffler and dual 2.5" out if that means anything.

The setup will be (as of now... it keeps growing lol):

Stock bottom end LQ4
EPP cam
LS3 heads
PT76gts @ around or less than 10 psi
.96 a/r

Do most people run through a catback with a cutout? Or do they dump it? If dumped, how loud is it? I know the turbo will act as a muffler to an extent.

Thanks for the help

ilovechevy1

iTrader: (4)

i would love to hear the answer to this one as well man..I'm doing a turbo kit and kinda want to keep on Borla cat back on,,they look sweet

1Legged60ftHnter

I don't care so much to keep the muffler as I do to keep the tips. My car would look gay without tips. lol

Fb0dy0nly

iTrader: (10)

cutout definitely I would add in there. Do as large pipe as you can to the cutout and then have the other side of the cutout go down into your 3'' catback if you want to keep it. Most guys just run the DP into a "turbo" type muffler, aka, very litttle anything inside hindering flow. Then dump it under the car. Unless you have a race car and then it usually gets to exit before or right after the front tire thru a fender. You said you needed tips for your car to look right, well why not thru the front fenders?
With the added turbo, the car doesnt "sound" super loud and rumbly all the time like n/a as the gases are being used again and not driven out the rear of the car constantly at such a high rate. It will still scream at WOT tho!

Nitroused383

iTrader: (10)

I run my stock slp dual dual muffler most of the time. I have a 4" electric cutout right after the down pipe and it's ungodly loud when open. I love the way it sounds through the dual dual, still has a nice rumble but not annoyingly loud. It does cause a little slower spool and probably is a restriction of around 30 + hp. I still managed to make 720 rwhp with a stock bottom end ls1 and 76gts on 11.5lbs through the stock dual dual

Tally TransAm

iTrader: (17)

you can run it but throw a cutout in there. i lost +/- 30 rwhp and noticed substantially slower spool by just adding a 3" muffler to the end of my downpipe. it lasted all of 1 week before i took it back off

Sarg

iTrader: (6)

If it is a fairly straight through design and not a multi-chamber muffler, I am sure it will be fine. It is more a function of design than just having a muffler. I plan on using twin 3" Magnaflow straight through style mufflers on my twin turbo build.

A cutout is not mandatory by any means.

Orange99Z

iTrader: (25)

With my first kit, I tried it with my Magnaflow catback. Frost told me to try dumping it under the car before he final tuned it. The car picked up noticable power without changing anything else. It spooled quicker and pulled harder & longer up top. I used a 3" Dynomax Bullet w/ a turndown at the axle.

Now with my truck manifold kit, I used a cutout to dump at the axle or to use the Magnaflow. I haven't compared the difference from open to closed yet.

1Legged60ftHnter

Well... I suppose I'll try to keep the hooker probably and just put a cutout as close to the turbo as possible.

1Legged60ftHnter

Any more input on this?

skinnies

iTrader: (33)

Run some straight through mufflers, my ltd has dual 3" and 6 mufflers all straight thru so its silent! I haven't got it on the dyno turned up, but at 140mph at 3700lbs it didn't change mph really thru the mufflers or vs the 3.5" cutout(before the dual 3").

My2kz28

iTrader: (1)

Does anyone have a dyno comparison of a turbo car running with the cutout open for one run and closed for one to see hard numbers? If no one does i will..im putting a cutout on the exhaust of my front mount gt45 kit..i should hope to see some concrete proof they help turbo cars..

1Legged60ftHnter

Also interested in knowing dyno results. I think what I will do is run the exhaust out through the catback and just have a manual cutout for now. If it holds me back 30 hp I guess that just saves the ten bolt that much longer. lol