Simp

First off I will say that I love the sound/performance of my true duals. But I have always wondered how a dyno comparisson of an open cutout y-pipe setup would compare to true duals. I've heard that the peak HP numbers are similar, but the duals make better power under the curve. Anyone have back to back dyno numbers?

The reason that I'm asking is I'm planning on lowering my car soon and am extremely worried about clearance issues with my 3" TD's. I live in Atlanta, with some of the worst roads ever, and have already scraped the duals a few times on stock ride height. I'm thinking I need to go to a cut-out/Y/cat back system or perhaps 2.5" duals.

mrr23

iTrader: (3)

yes i did back to back runs. but this was over stock exhaust. gained 11/13. but at the track, did nothing for the 1/4 mile. but did change what happened in the quarter. it moved the power curve upwards. look at the 60ft and 1/4 mph.

cutout closed ----- open
60ft - 1.987 ------ 2.074
1/8 - 7.902 ------- 7.912
mph - 93.20 ------ 93.97
1/4 - 12.102 ----- 12.080
mph - 117.12 ---- 118.06

Full-Force

iTrader: (11)

does that formula have nitrous on it?

LS1LT1

iTrader: (16)

So this was just a Y pipe with a cut out closed versus open right? No duals involved I assume?

I wouldn't exactly call that nothing in the 1/4 mile dude, you gained some nice trap speed uncapped.

Z28Venom

iTrader: (13)

My first setup was the Pacesetter ORY with dual cutouts. Lemme tell ya, that thing took away alot clearance.

I'll have pics this afternoon of 2.5" TD's lowered with the Eibach Prokit..

Simp

anyone else?

mrr23

iTrader: (3)

yes. 200 hp to be exact.

mrr23

iTrader: (3)

all stock exhaust http://www.stealthram.com/qtpcutout.html let me clarify. did nothing for ET. but lost 60ft to gain 1/4 mph.

Simp

anyone know anything else about the topic?

Jorday

When I switched from a y pipe to true duals I only gained approx .1 ET and a mph or two.

Simp

Was that with an open cutout or closed?

Lucian

iTrader: (1)

do you think that the longer ft times would be due to a traction problem. So possibly if you were able to hook the tires up a little more then you would have a little better time. Just my opinion from looking at the numbers w/out seeing the actual track run

Lucian

iTrader: (1)

what setup did you have before and after (i.e. cats, headers, type of y, type of catback)

that all could play an important role in the gain from one to the other

Jorday

I had macs with off road pipe and an SLP dual/dual catback with a cutout,
I switched to thunder LT headers with an all 3 inch true dual system with x pipe, bullet mufflers and turndowns.
I didn't use cats on either setup.

LS1LT1

iTrader: (16)

Yes that could be a strong possibility as well, more power often equals less traction of course.

2MuchRiceMakesMeSick

Who has ran both cutouts with y AND true duals in two different setups? Which gives you the lowest times? I have true duals and im thinking to switching to cutouts with y pipe. Will I gain any time/power?

2002$$

no a y-pipe doesnt net you very much flow....the x-pipe however gives more velocity,therefore yielding more torque(under-the-curve)which is something you always want. duals flow more freely,and ive heard that a crossflow muffler;especially Slowmaster,only support up to 350-horse.....maybe your making more but couldnt get it through that muffler....TD's ALL THE WAY! plus when i open my cut-out's i LOSE power! it sucks;i guess my exhaust is already free-flowing enough,that the c/o doesnt gain me any flow.it saps the low-end hard and doesnt really yield you much more top-end...sounds sick,though.

WiseguyZ28

Can u open electric cutouts in the middle of the run? How bout trying to get the best of both worlds. Start out with it closed and then open it bout halfway down the track. I have FLP's w/ory and a gmmg but am thinkin of gettin the TexasSpeed True Duals but here's the question, if i get a cutout then would i be making the same power as true duals or something minimal or would it be a good difference.

2002$$

i think w/ a full cat-back;youll make a little more power,BUT if you want to get a lot of torque-under-the-curve....go with the TD's they make a lot more power.IMO.

mrr23

iTrader: (3)

zero traction problems. burnout so good that smoke was coming up through the center console. i come out on the motor. then at 2000 rpm hit the bottle. i made about 5 runs that day with it open. then i closed it, and voila the 60ft came back. there i a video of one of my runs aver at need2speed.com bradenton track day. 5 minutes long at 4 minutes is me and a pewter TA going at it. you'll see the burnout.