My two cents.

A car with stock manifolds and cats:
GMMG sounds the best, then Borla then Magnaflow are next.
All will net the same power gains.

Things get different when you go LT's and no cats because you will get rasp around 2K RPM at light load from mufflers that are straight through. The rasp is ugly and sounds like sheet metal rattling or some also call it the machine gun sound. The problem stems from the convergence of the two pipes behind the headers into the single pipe running to the back of the car. It is believed that the gases and velocity of the flow just does wierd things right at the Y.

If sound is not an issue, all straight through catbacks will net the same gains. The GMMG especially and the Borla have terrible rasp IMO. The Magnaflow has a bit less rasp and that would be my pick if you want a rather straight through catback and sound is a bit less of an issue.

A chambered muffler like the Hooker sounds the best with LT's and no cats because it muffles much of the rasp. Some will argue that the chambered muffler does not flow as well as a straight through muffler. I feel they are all in the same ball park personally.

I recently had LT's and the Borla and hated the rasp so much that I went TD's. I have the best performance and the best sound with no ill effects like rasp or machine gun but that is an expensive way to go and a lot of work (see sig for pics). To me, awesome sound trumps performance but then again I dont race and I wanted the benefits of LT's and no cats.

 

But I have always loved Flowmaster for the LT1's. My olde 355 hot cam'd car with crappy Edelbrock shorties had an 80 series muffler with an otherwise stock exhaust and it rocked (the muffler was a 2.5" inlet, dual 2.5" outlet). The word that best described that setup (what observers most commonly said) was that it rumbled. Great low RPM bass (like a big *** diesel schoolbus) and wicked high RPM scream. I wouldn't say my old exchaust was raspy at all.

I've always hated the RASPY exhausts especially Borla. I don't doubt that a borla unit with full open plate (muffler by-pass) will give you the most HP assuming its a 3" pipe, but that sound is horrible.

When I was accumulating a mountain of parts for my new 383, a Flowmaster was the only exhaust on my radar. I'm running their American Thunder cat back - 3" piping all the way, in & out of the muffler, with gorgeous 3" slash cut stainless steel tailpipes that are slighly angled down. I don't think the muffler in this kit is an 80s' series (its much larger than my old mufler), but it is a chambered muffler from what I undrestand. Up front I'm running the LPP stainless LT's & Y-pipe with no cat.

I'd love to post some videos of the new exhaust but even the few I have don't do any justice whatsoever (videos never will unfortunately). I will say that the new setup is really loud (I mean REALLY - I was shocked). I remember guys telling me the American Thunder wasn't loud and that I should go for something better - I think those guys were freakin crazy.

Here's one small idle clip made from my crappy iPod mini which I've recently lost. Driving in the car the engine sounds awesome - at about 2300-2500 RPM on the freeway it sends out this killer booming rumble - at 7000 RPM's it sounds like a freakin racecar.

http://www.youtube.com/watch?v=J4Rk-...layer_embedded

I've heard and seen the Magnaflow on our LT1 cars. I'd say it comes the closest (sounding) to the Flowmaster. IMO though those 3.5" exhaust tips look too big in a Camaro - maybe not so bad under a Trans Am bumber. Also, having now gone with the stainless slash cut tips I simply can't look at any straight cut exhaust tip the same anymore. Looks to boring.

I'll try to post a pic of my car just to show what the 3" pipes look like out back. Some may say they look too small (narrow) which is arguable based on tastes. I think it looks classy, perhaps a tad bit reserved almost stock-ish upgrade, but nobody will think its stock when the engine is one.

Flowmaster all the way on my car. Magnaflow would be my second choice based on sound. I think the Corsa system looked really hot with those dual slash cut pipes (but really expensive).

Oh ya, best part about my Flowmaster is I think I paid like $300 for the whole system a few years back in the US. Great deal.

 

PS - I'm fully expecting an anit-Flowmaster backlash here! lol I know, I know. I must be stuck in the past or something.

PPS - apologies for that awful IAC motor hiss in the vid! I was going to adjust the idle (blade angle and air counts) however before I got a chance to do so the PCM had learned itself and now the IAC motor actually turns off after a few minutes.

 

DVS_LT1, it called "old school" . I have the Pacesetter ceramic coated long tubes,y-pipe, and Flowmaster American Thunder cat back and love it! True old school muscle car raspy sound. It is pretty loud when I get into it,but the cops don't bother me. They are too busy with the ricers and their coffee can mufflers.

The others sound too muffled and gurguly to me.

I get compliments all the time on how my car sounds!

 

Flowmasters sound good on old carb'd motors, but I have yet to hear a good sounding Fuel injected car with them. I absolutely hated mine...probably the worst sounding and flowing aftermarket muffler you could buy IMO. The stock muffler gutted sounds better, IMO.

 

https://ls1tech.com/forums/lt1-lt4-m...ew-y-pipe.html

Might yield good info for you. i have the hooker aerochamber muffler and it is amazing. the car is very tame at idle to redline. When i get a better camera ill take a video of it

 

Still curious about what point do 1 5/8" mid length headers become overly restrictive? Would i still make decent power with say 230ish cam and minor head work. As of now i think that will put me in the ball park of where i wanna be. (about 360-75 ish whp) I know you will always get better performance from lt's but i will have a visual emissions inspection. Dont want to have to swap out stuff to pass. unless its a cat and a cut out.

 

I like Mufflex 4" with spintech muffler for LT1. The sound is like no other IMO.

Listen to that burnout http://www.youtube.com/watch?v=K41TM...e_gdata_player

 

This is your most cost-effective solution. It will sound great too.

 

Another closet Flowmaster fan here! I ran just the FM muffler, then the FM American Thunder cat-back, then a Borla, then Bassani TD, and now a Magnaflow race muffler.

Needless to say, I've wasted a ton of money on exhaust, and hindsight being 20/20, the FM was the best value and sounded best.

 

That car is a beast. Your C6 runs well too

 

Why thank you sir.

 

any takers on this question?

 

What is stopping you from passing visual emissions inspections with LT headers? Buy the models with EGR and AIR provisions. Or simply buy off road race versions and weld up fake EGR **** (that's what one shop told me to do - I didn't even bother).

 

I guess it just depends on where i take it for the inspection. But if the tech wanted to be a dick he could fail a visual inspection for the cat not being in the stock location.

Anyone in the st louis area have a heads up on where i should go?

 

If your car PASSES the e-test who cares about the visual inspection - usually its the other way around: if you get stopped and they start noticing things missing or misplaced, then they give you 48hrs to go to a designated test site for another test, OR worse yet they call over an MTO to sniff you at the side of the road.

Will your car really pass an e-test on its own? I'm confused. If it will, then again who cares about the visual stuff? (wrong/misplaced cat, etc - if it works then its legit. Tell them the new cat makes it pass emissions even better).

I'm sure there are enough places in MO that will hook you up with a pass test; just about any place up here for a $100 cash (in addition to the $30 something test fee) will type your VIN number into the computer then back another car into the rollers for you. Look for the shops that keep a resident crown vic on their lot lol.

Not sure how strict they are in your state, but I'd think as long as you have some form of cat (fake or not) under the car you should be fine from visual side. As for the EGR/AIR crap as said you can get LT headers with those provisions (and use them, OR block them), or weld phoney EGR pipes into the off road versions just to pass a visual.

Its interesting to note that the factory GM LT4 engine in the C4 did NOT run an EGR system. Those Lt4 red intakes came from the factor with their EGR chambers blocked (I also remember people claiming certain manifolds were actually cast without the EGR openings in the back). The reason for this was due to the factory LT4 cam profile (increased overlap?). I wonder if the few special edition LT4 F-bodies came with EGR setups or not...

I also wonder if, in a tricky situation, you could pull a Mr. wizard on a cop or inspector and say your engine is a factory LT4 which was not offered with a factory EGR setup. Tell them: "Sure, that's the stock 115 LSA cam they hear chugging/chopping away!"

 

The only tests they do here anymore is on 96 and newer vehicles. Just plug in under the dash. Anything older than that is a visual inspection. No rollers. I guess i just need to jump on the local forums and find out where other people take their cars.

 

im going to be one to go against the magnaflow, i personally dont like the sound at all, its raspy in certain spots and WOT makes you sound like every single other F body around.

have some 2.5 inch over the axle true duals built for your car, i think H pipe or no crossover sounds the best, but some people enjoy the exotic sound of the X pipe, as for mufflers, you need to stick to a bullet type for the most part but you may be able to fit a small chambered one like a flowmaster 10 series.

catback? ill have to say i like my edelbrock although it robs some power, and i also like the spintechs.

 

Heres my .02
I just got my stainless steel LT's with matching Y pipe from eworldsales for $285 shipped to my door.

I've got a 94 so I'm not worried about emissions, here in Chicago we dont even have to take it in for a visual inspection.

If you've got all winter to wait for a good deal, I would say keep your patience and you'll find the deals your looking for. I just picked up a magnaflow stainless catback for $125. I've also got a qtp cutout to open things up if any ricer is dumb enough to pull up next to me.

I dont have a video of it all set up yet, I should be getting it put on later this week or hopefully next week. The SS really gives it a more unique and expensive sound haha. For a little over $500 for everything including the cutout I dont think I could have done better. Good deals are out there.

I am lowered with eibach springs and 17" wheels and it's pretty close to the ground. I do scrape when I go over train tracks too quick, but it's really more how you drive the car rather than how low it is. I really dont mind scraping every once and a while, I cant tell you how much it helped my power up top in the RPM's. I usually just shift when I feel it get a little sluggish around 4200-4500, but I've caught myself going well over 5000 now just because it keeps pulling and pulling

Sorry I dont have any input for the power gains other that the fun factor. One last thing to think about. If your planning on putting on the headers yourself, you will definitely want to only do them once so make sure your going to be happy with whatever you put on. Either way, you'll love it, good luck.

 

I believe that the one you want is item number #15620. Also on ltxtech.com in their sponsor section there is a deal on them for $385 shipped. Thats a good deal on one normally they are around $430 i believe.