Crazy julio

What makes better power, an open cutout or an aftermarket 3" exhaust?

I'd think think the coutout would because it completely bybasses the exhaust, but it supposedly only picks up 5-10 compared to the exhausts 15+.

What kinds of #'s would one expect from both choices if it's already equipped with LT's and Y?

teke184

actually, most guys see 5-10 hp gains with a cutout ON their catbacks...
and real world gains are 10hp with a good catback and another 5 hp with a cuout open.

the advantage of a catback is a good gain all the time, with minimal noise hassle, and then have the $30 cutout installed for times like the track.

and remember a cutout on a bone stock exhaust wont gain the same power, since stock pipes are 2 3/4" compared to 3" catbacks.

Crazy julio

but it cuts off before it gets to the 3" catback, right?

teke184

i thnnk you are a bit confused. the cutout typicallly goes in the intermediate pipe, on a catback this would be 3", look at this illistration from qtech

now if you put dual cutouts on the ypipe you would be bypassing the catback. those pipes would be 2.5" not 3".

Crazy julio

I thought it was put on the Y, not the catback
or is it on the pipe leading from the Y to the catback

If you just got a 3" Y, and a cutout, and put the cutout at the straight part of the Y?

wouldn't that be like a 3" catback with a 3" Y except better?

rncotton

I picked up 13 RWHP when I opened my cutout.

Hypertech's dyno, controlled runs, coolant temp at 180* at the start of each run. Mods: Lid, Cutout, 160* t-stat.

317 RWHP with the cutout closed, running through stock WS6 exhaust and Flowmaster muffler

330 RWHP by opening the cutout.

teke184

now i'm confused...

the catback IS the pipe right behind the Ypipe.

you either put a cutout in the catback (in the Intermidiate pipe from the ypipe to the muffler) or you put two cutouts in the Ypipe itself, basically one after each manifold.

does that makes sense?

Buffdaddy

The last I heard is that the cutout will gain more than any 3" catback.

coogsLS1

cutouts!

Crazy julio

Well, it's called a "Y" pipe because it is shaped like a Y (Two pipes going into one)

My point is that If you leave the exhaust stock then get a 3" Y

then get a 3" cutout and put it at the part of the Y where it's one pipe

it should be the best possible exhaust, because you completely bypass the exhaust, and you wouldn't have any resistance from the flat Y

teke184

the best possible exhaust would be two cutouts on each side of the Ypipe, before the join.

a single 3" after the Y would would well, but there is not really room there for a cutout. that is why most people put the cutout jsut before the axle, there is a pocket there that the cutout tucks up into nicely.

what you could do is run some cheap 3" pipe from the Y, back to a cutout before the axle and then weld the back of the cutout to the stock exhaust pipe. this way you take advantage of the cutout, don't lose anything to thinner pipe, and have good clearance with the cutout out of the way. you'll also have less interior noise since the cutout is farther back...right undre the front seats would get so annoying you'll never drive on the street with it

99BlackTA

Should the cutout be before the cat. converter or the muffler??

david97gsxr

it should be before the muffler, if it wasn't you wouldn't notice much of a difference.

Crazy julio

Yeah, thats what I was thinking.

teke184

before the converters is a good idea, since you'll be bypassing the restriction of the cat AND the muffler.

however, depending on the car you won't be able to do this.

on the 93-95 lt1's i beleive you can, since the cat is farther back in the Ypipe, but i think starting in 96 with the dual cats there is a cutout bolted right to the manifold...no room to put a cutout before it. i know that's what the LS1 is like.

so it is possible your only choice is after the cat(s)