FASTFATBOY

iTrader: (23)

Motor makes close to 600hp at the flywheel, at present it has 1 7/8 headers. 3.5 inch Y pipe, 4 inch Mufflex with a single in/out Magnaflow muffler.Does NOT have a cutout.

I have never uncapped the car, was tuned and has always been run capped up.

Is there any power to be gained by 3 inch true duals OR a cutout?

3 inch true duals would be VERY hard to do on this car.

My other option is to cut the Mufflex under the passenger floorboard, put the Magnaflow muffler I already have there and turn it down in front of the axle under the car. Anyone see any gains by doing that?

Just trying to get some more power out of the car.


David

JL ws-6

iTrader: (50)

IF you suspect that the exhaust is choking the car, try removing it and make a dyno pull before and after.

I went thru this last year, I had 1 3/4 qtp headers, a gutted catted qtp Y and a LM. The car made 477 rw with the exhuast on, took it off and it made 474 LOL. I lost power, but, the car lost 50 lbs of exhaust, which is more what I was after at the time.

I don't know how restrictive a 4 inch exhaust could really be, I had a 4 inch collector off my Y pipe, but with the LM it necked back down to a single 3 inch after the resonater. That being said, I doubt your exhaust is a restriction, but it may be rather heavy.

TS6

iTrader: (41)

I went from 3" duals to a single 4" and lost no power, and the 4" setup was lighter. It is dumped at the axle.

GS WS6

My car has a 3" Y-pipe with 2 bullet mufflers in it, into a flowmaster dual 3" into a single 4" y-collector, into a 4" mufflex.....car made 499rwhp through the exhaust and made 502rwhp open headers........

It made little to know difference on my 383 setup

Stang's Bane

iTrader: (22)

I would leave it alone.

94 guy

iTrader: (125)

jl ws6 did your y pipe neck down to 2 3/4" where it slipped into the LM? i have that neck down on mine and was wondering if it hurt any?

Getav8

I'm running a similar setup to yours only different is the person I got it for works for thunder racing and they modified a 3.5" hooker aeromax (think thats as big as it comes) to use the 4" pipe in and out. He had it on his car which was putting down around 485ish at the wheel, and he said he lost nothing going from open headers to this setup on the dyno.

Lonnies Performance

iTrader: (16)

I had dyno info at one time that showed a dyno pull with a supercharged LT4 making over 800rwhp that gained less than 5hp by removing the mufflex. The only ET change may be removing it entirely as it will weigh close to 40lb.

There is essentially no flow difference between dual 3" & single 4". I have 3" duals on my Camaro & they are hard to tuck up under the car if you want them to the rear bumper. After all the money & time for the 3" duals, I wish I would have went with a Mufflex.

FASTFATBOY

iTrader: (23)

UPDATE!

I took the car to the track today, made 2 baseline passes and then uncapped the car.

It picked up NOTHING, NADA, ZIP, ZILCH!

SHows you how effecient the 4 inch Mufflex is with a single inlet/outlet Magnaflow muffler on it.


I was very suprised.


David

AutoRoc

Thanks for sharing the results! I believe this way is lighter and sounds better...A little smoother.

FASTFATBOY

iTrader: (23)

I kinda missed what you are getting at, the Mufflex is heavy as hell, but I will keep it. Keeps it somewhat quiet and puts the exhaust outlet at the bumper.


David

Z-RATED94

iTrader: (6)

David, you ever finish up the nitrous install?

StreetStalkerZ

iTrader: (1)

Some of you mention loseing HP uncaped exhaust vs. through the muffler. I have a 3" H pipe setup with Borla XR-1s mufflers dumped at the axle with 3 1/2 inch cutouts welded past the o2 sensors for open exhaust.

On a local mustang dyno i did 447 rwhp through the Borla mufflers then uncaped the cutouts and did 412 rwhp through the headers torque was about 3 ftlb. lower than the muffler as well. I always thought running open exhaust was the best way to unleash power but mine did not like it at all!

Villain281H

iTrader: (5)

Good to see it wasn't costing you any power. IMHO a single exhaust looks cleaner, doesn't lose the ground clearance a dual system does and in most cases below a certain rwhp/rwtq figure, doesn't lose any power. Always good to see another myth/thing most assume proved wrong.

Derek

FASTFATBOY

iTrader: (23)

Yes, but for some reason the car will not start with a Accel 375 retard box online. I havent figured it out yet, and without it I cant use the spray. WIth it unplugged and just the 300+ box hooked up it runs fine.


David

LS1 SPEED

iTrader: (22)

I'm not surprised with the Magnaflow muffler, but a Spintech or Flowmaster would have cost you some power from what we have seen.

JL ws-6

iTrader: (50)

My new setup consists if a pair of super 44's that the ends were cut off and 3.5 inch pipe runs in and out of them.

Sounds awesome, and mated up with the 3.5 inch collectors on the new kooks headers perfectly.


I can't see this being a restriction, 3.5 inch pipe is BIG, and with 2 of them, that's about as open as it gets

TJ

iTrader: (10)

ive been debating the same thing.
i really like the ground clearance of the 4", but always thinking about a dual setup.

kp

iTrader: (34)

I have 1 7/8 QTPs into a 3" Y-pipe/flowmaster merge to a single 4" magnaflow muffler dumped before the axle and the only thing I gain with open headers is a visit from the sheriff every time I fire it up at home and a headache at the track.

JL ws-6

iTrader: (50)

That's funny as hell LOL. I put an exhaust on this year not because I was having problems, but some of the tracks require it for some classes, plus englishtown you have to have it. I went with 4 super 44 mufflers, and just cut the hat off to make the inlet 3.5 inches in diameter same with the exit, put the mufflers probably 16 inches behind the end of the headers where the indents are in the floor, then ran probably another 18 inches of pipe off of them and aimed it out in front of the rear tires.

It's not quiet, but it's way quieter then open headers were. I think it's quieter then the car was with the cam and the LM on it to be honest, and with 2 3.5 inch pipes, how restrictive can it really be? A little flat black high temp paint, and you can't see it at all from the side too, which is nice. I weigh'd each 1/2 (2 pieces, one for each header) and it was about 18lbs, so it's not that heavy either someday when my fab guy sends me the pictures we took, I will post them.