I am currently working on turning my car into somewhat of a sleeper. My plan is to use a stock or small exhaust system (cat back so I can still use my long tubes) into a fairly quiet muffler. I do not "need" a cat in Illinois, so I would put a cut-out there.

The main question is, would a stock diameter pipe with a cut-out be able to flow enough, or would I need a larger pipe. If a larger pipe was needed, what size would it need to be. The engine should be able to produce 350 horsepower at the rear wheels.

 

here is what i'd do if i where you:

since you have lt's, you'll need to build a y-pipe anyway....so, right before they y itself, build you two cutouts, one for each bank, then run into a 2 1/2" dynomax catback, which has an extremely mellow, almost stock sound to it. also has the two hideaway style tail pipes for the stock look.

 

If I were to stick the cut out back a little, past the y pipe and where the cat went, would it flow enough or become a restriction?

 

I have an electric exhaust cutout set up right before my cat. I'm running 3" dynomax exhaust, it sounds like stock, but floes better.

 

I have a 3" Hooker catback, and a cutout in place of the cat. Sounds pretty tame untill you pop the cap off.

It wouldn't be so quiet on a hotter motor though... I'd suggest a 3" system with a 3"in/dual 2.5" outlets, and put a bullet muffler just after where you put the cutout on.

 

my idea would work better i think. but you'll have to fabricate your own cutouts. look at the way a regular cutout is made and make a set into your y-pipe before the y junction.

 

I had a 3" hooker cat back with a 305, it did not sound stock. I would not put a bullet muffler on the end of a cutout. That defeats the purpose of having a cut out, no muffler or further restriction.

Dual cutouts at the header would work, but only while the car is moving. If the car is sitting still, you can be breathing in CO, which is bad. That is why I am wanting a cutout at the old cat location so it can point out away from th car, or before the rear axle. I ran open long tube headers for a while, I did not like the carbon and the like that changed the bottom of the car black. Sure you can point them down, but the gas will just hit the ground and then float into the cab. Which is also bad.

 

hmm...well, i run dumps right in front of the rearend and drove the car EVERYDAY for two years like that and never had an issue with CO in the car enough to actually make me sick.

and people run open headers all the time, it's not as big of a deal as you think.
the cutouts also wouldn't be open all the time, cause that would defeat the whole purpose of building a sleeper.
and the bullet idea was like this:
ypipe-cutout-bullet-ipipe, not bullet after the open part of the cutout....just trying to figure ways to keep the car quiet. i still think that the dual cutouts with lt's would work the best...besides, how are you going to run pipes to the stock location with longtube headers? the collectors go WAY out past where stock pipe runs for the y-pipe.

 

I think you misunderstood... I meant to put it after the cutout on the exhaust pipe, not on the cutout opening.

I missed the part about longtubes... yes, if you are getting longtube headers, get a pair of 3" cutouts, and use them right on the collectors.

 

Dynomax is quiet just like stock... I found that out by mistake

It's great to be able to flip a switch and open the cutout right at a traffic light.

I had a Ram Air T/A back down on a race when I was at a light. He pulled up, downshifing to the red light. Looked over at me and tapped the gas a few times taunting me. I shut my key off, flipped the switch and started the car back up. The look on the kid's face was priceless! Little did he know, he backed down racing his LS-1 against a "stock" LO3 305. haha

-Jim