rob69zombie

iTrader: (7)

I have a couple of quick questions reguarding exhausts I figured you guys could help me out with. My buddy's 02 SS put down 414rwhp cam-only with a 6 year old Patriot 226 cam. At the time he was running Pacesetter LT's, ORY, and his factory dual/dual. He wanted something a little louder so he got a LM1 and replaced the resonator with a 3" stainless Sweet Thunder chambered muffler. IMHO, it was the best sounding cat-back I had ever heard on one of our cars. He went and had it re-dyno'd and his first run he put down 367rwhp! The tuners (Mayhem Motorsports, NC) were so surprised that they dropped the cat-back right there and did another quick pull. This time it shot right up to 407rwhp. WTF??? Is the Sweet Thunder and other chambered mufflers so restrictive that they eat that kind of power? They told him that Magnaflows and Hookers make the best power out of all the cat-backs. He asked them about my GMMG and they said that not only are they heavy (duh!), but they don't flow that great either. Now I can't imagine losing 15rwhp or more over a different cat-back but I don't know now. I HATE Magnaflows and Hookers are nice but almost always get the death rattle so I'm thinking about going to a LM1 or 2. Anyone else go from a GMMG to anything else (besides TD's) and pick up anything??? Thanks for any advice!

matt224

Should have tried the LM resonator too, I can't see them being restrictive; the LM1 is pretty damn close to a straight pipe.

Element

iTrader: (5)

The 3" Sweet Thunder doesn't have an actual 3" flow path, as far as I know. I can't see it eating that much power, though.

MikeWS6

I have also heard that LM1 and Hookers flow the best. I have no experience with gmmg but they are said to flow well. Maybe thats just to justify the price?

rob69zombie

iTrader: (7)

The LM1 DOES flow well. He just replaced that straight-through resonator with the Sweet Thunder, which as stated necks down to about a 2.25" flow-through. It sure did kill it though. Mayhem said that it had a lot to do with the position it was in. It was in the I-pipe meaning that 100% of the exhaust was flowing through that single restrictive tube. I was just wondering if the GMMG flowed OK because it has 2 seperate chambers or does it suck too? lol

1979rs/z28

iTrader: (21)

Keep what you got lol.

rob69zombie

iTrader: (7)

Fair enough Jamie. I like it quiet anyways.

SSickLS1SS

gmmg is sex tho.

rob69zombie

iTrader: (7)

Yeah, it's alright. I like mine OK. This site is all GMMG nutswingers though, lol.

djfury05

iTrader: (30)

so what were his final numbers then? Fast 90 went on and what else?

hitmanws6

iTrader: (20)

GMMG flows very well, it splits into 2 2.5 inch sections, I gained nothing over it with my cutout. As far as sweet thunders go they neck down 1/4 of an inch, I find it hard to believe that it cost you that much power unless you got an older one that necked down a lot, but even the LM splits as well.

mean_greenZ

iTrader: (1)

that sucks! i'm glad i got rid of mine. someone on here had this happen with a moroso spiral-flow too. I like dynomax or magnaflow mufflers. straight thru with a perforated tube..no louvers, chambers or reduced flow path to restrict it. However the slp LM2 muffler necks down to about 2.75" IIRC, the LM1 does not. And also the muffler inlet on the magnaflow catback necks down to 2.5"-2.75"

MUSTANGBRKR02

iTrader: (91)

It shouldn't be hard to understand. Pulled in got a pull did numbers XXX. Put on lift removed muffler and it did xxx+30 back to back runs nothing changed which was within 6hp off first dyno tune.

Element

iTrader: (5)

What do the under-the-curve numbers look like between the two runs?

1979rs/z28

iTrader: (21)

They were horrible, car didn't even make 340 ft lb's of torque.
It has a 3'' dynomax bullet that dosen't neck down at all now and everything is well.

MikeWS6

hahaha your sir are correct.

BenLaz

iTrader: (6)

Gained 2 rwhp when i opened my cutout...

Dual 3" y-pipe to a 3" cutout then to GMMG... (cutout is right after a proper y-merge)

This is on a TH400 H/C car making 465 rwhp... So i'd say the GMMG flows A-OK...


As for the moroso spiral flow comment above... that was me... if you search my user name, you'll see i lost nearly 50rwhp when i put one in my I-pipe infront of my GMMG... was making around 420 rwhp at the time.. installed it and went down to 370rwhp... took it off on the dyno... HP shot right back upto 420rwhp.

rob69zombie

iTrader: (7)

After seeing my buddy lose 35rwhp with a sweet thunder, I believe you. Glad to hear yours flows; that's what I was hoping for.

FF88

on my z i ran pacesetter LTs and made no power gains, bought a set of jet hots on here loved them..i ran 3" stainless x-pipe (borla) to gmmg mufflers, it sounded amazing with my little tr224 cam... but if you want to go with a cut out they are fun and usefull as well...

RevGTO

iTrader: (12)

I got rid of my GMMG because of weight. I had powerpack in the I (true 3" flowpath), resonator tips and a catted Y to tame the rasp. I went to a single exit Hooker MaxFlow (3"in/3"out) which is top-flowing and MUCH lighter than the GMMG setup. I didn't see any gains until I replaced my 2.5" catted Y with a 3" ORY. The ORY was impossible on the GMMG because of loudness and extreme rasp.