Well I've had my firehawk for about 8 months now. Ever since I got it I've been trying to figure out what exhaust I wanted to run. I am probably going to run pacesetter hearders because of value. Not running any cats. I've pretty much decided to go with an x pipe setup. I have read the sticky's, (promise, I even have most of it printed out.) I have went to ls1sounds, and I have tried (without luck) to listen to some in person. I have a few questions/concerns I would like answered before I decide on one.
In case this factors into the answers my current mods are only a lid and exhaust work. But since I'm redoing exhaust I spose my only mod is a lid I will want a lot more work on the car eventually. at the very least a small cam. but more likely I will want FAST 90mm intake and tb, a mid sized cam, some type of headwork, possibly forced induction and/or nitrous. So with that in mind I want of course great sound and performance (doesn't everyone?).

should i get emmisions fittings on the headers? over or under the axle? 2.5 or 3 in pipe? and what set up have you had experience with?

the tsp rumbler td setup is appealing but havnt heard any first hand and havn't really looked at many others. and I don't want them dumped. so answers to these questions and any other info would be greatly appreciated.

 

If you go with a true dual set up your car is going ot be very loud with a cam and longtubes. I have a hooker cat back with pacesetters and a cam and it is loud, but not too loud till I put in the cam. If your car is going to be daily drivin I would not get the true dual because you will **** off all of your neighbors. If for track use or an occasion weekend car I would say go with the true dual because everyone will know you are coming.

 

thx. well by the time I start cammin it I might have a beater car. If not my wife and I will be driving her eclipse most of the time which is much quieter and gets better gas mileage.

btw I DO want loud. I want it to hella loud at WOT and loud doing everything else even idlin. i like loud...

thx for the input black01

 

Ya I like loud, thats why Im puttin a cut out on next week. nothing like starting up the car to go to work at 5 in the morning with the cut out open. Im gonna **** off my neighbors.

No prob 10thAnivHawk. good numbers for stock and the conditions.

 

A tru dual does not have to be loud, it all depends on what mufflers are used. a 2.5" system will support 500 HP w/o any back pressure restrictions (depending on mufflers again). Over axles provides better ground clearance.

I had an H pipe 3" tru dual on my IROC, i think it was before the 383, when it was the 355 ZZZ motor. It sounded great. IO received comments everywhere I went. I had flowmasters (didnt know better, and not as many choices back then). I think it would have been better toi have gone 2.5".

Even now as I contemplate one again, I am thinking of 2.75" although, that tube size isnt as common, and may end up costing more than 3".

My IROC didn't have a lot of low end torque, I ended up removing the tru duals, going with hooker 1 3/4" LTs and a Gale Banks cat back. I did that right before or right after stroking it to a 383, and it felt much more resposive down low. sowmuch so, that first gear was useless

 

another question I had was what size headers to use 1 3/4 or 1 7/8 I was thinkin 1 3/4 would be better until I get n20 or boost but I'm not sure

 

1 3/4 for stock cubes. 1 7/8 for strokers (383, 396) 1 7/8 stepped to 2" for bigger cubes 418, 427...

 

First off, don't listen to all this CRAP about TD's being loud! I mean a golf cart can be loud if you want it to be. A poorly designed system and an idiot who buys it then complains about the noise is no excuse.

Corvette's and Mustang's both run duals and are no louder than an Fbody STOCK for STOCK. And most after market Y setups are fairly quiet because a lot of them run crap mufflers which restrict flow.

As for your setup, well here's what I've been designing.

Pacesetter LT's Coated, full emission.

EGR is not such a bad thing, and remember you might not live where emissions are an issue yet, but you might move or new legislation be brought in.

EGR also has ZERO affect on BHP. And some may argue that as it lowers PEAK combustion chamber temps it also helps to prevent detonation.

AIR, this is for the CATS. In order for them to work effectively air is pumped into them from outside. Again has ZERO affect on HP. AIR also only runs for 20 seconds or so after start up. I'd leave EGR and possible remove the AIR system, becuase I'd also run CATS.

Random Technology 7000 Series 3" in/outlet Metal Matrix CATS to be precise. These flow ~580cfm so will not affect flow on 500bhp engines. These do not require AIR hence you could remove it. They will keep you legal however.

I'd then neck it down to 2.5" tubing, this will be fine for 500bhp, and even beyond this it will only have minimal affect on flow unless MASSIVE bhp is required. 600+rwhp. 3" tubing will be more of a pain to route and probably cost you some low end grunt, especially for a bolt on car, less so with a cam.

Maganflow 2.5" X pipe, this flows very well and I have seen reports of it outflowing many other X pipes. It's also stainless.

You'll then need some mufflers. I like the chambered style. There are two brands available.

1. Stainless Works
2. Powerstick

The Stainless Works ones are funnily enough stainless steel. I have not so far been able to find any flow rate numbers for them, but I'm certain their 2.5" muffler must flow in excess of 550cfm, which is all you need per bank for 500bhp. If they didn't flow well enough the 3" must, so you'd need a 3" X pipe, then neck it down to go over the axel.

Powerstick, I know they flow enough. According them a 2.5" muffler flows 1000scfm. Powerstick claim their design is better than the compition, I'll let you decide. The only downer is they are only availble in aluminiuised steel so will eventually rust through.

Obviously the Powersticks are cheeper as they aren't stainless.

I'd put the mufflers right after the X pipe and before the axel. The longer the muffler the better as it will help keep the noise down, and will have minimal affect on flow.

Then up over the axel, both pipes together on the same side for clearance issues. You can get a 3" Y through there so two 2.5" pipes will be fine. This is where 3" would not work well. And don't go under the axel, it will net you no real gains. Exhaust gases are perfectly happy going round bends in tube, as the flow rate will still be well beyond the requirement of the engine.

Then simply add some tips, personally I'd go for 3" slash cut, one per bank.

If the exhaust was too loud you could add another shorter chambered muffler after the axle, one per bank.

Here's a bad drawing of a possible layout. You could move the X-pipe to be more central and have more equal length tubing to it, but I think that would be harder to route, diminish ground clearance and yeild little gains. Also with the X the exhaust flows cross over. So the total lenght of the pipe will be similar, as the shorter one to the X-pipe has a longer path from the axel back to the tip (not that it's worth anything mind).

Also this system is not ZERO loss, but it should be minimal or low loss. Zero loss as you knows requires a resonator as per the sticky.

 

thats some good info 300!

Here's a picture similar to what you drew. I've posted this several times as something that I'm looking into doing:

 

My favorite TD setup so far has been:

Pacesetter Coated LT's (Race Style)
3" Custom X Pipe (no cats)
2.5" Sweet Thunder mufflers
Turn downs at the axle

I personally don't like the sound of sweet thunders ran all the way out the back, but that's just me....Your duals can be as quiet or as loud as you want them. I've heard, not personally, that magnaflow ovals and running cats are really quiet and sound great!

Good luck in your search and remember it's always better to do it right the first time!!

 

thanks for all the great info! Lots of help in my decision.

I agree that its easiest to do it right the first time

 

TD's dumped at the axle are loud as hell. No way to quiet them down without cats and real mufflers and/or going over the axle. Ground clearance sucks for 3" systems.

A good flowing Y-pipe (i.e. scavenging merge collector) and free flowing muffler perform as well as an X-pipe, and keep your ground clearance.

 

I have 2 1/2 inch true duals on my 2000 Camaro SS that goes over the axle and exits out the rear from beneath the bumper in the stock location. I left the stock manifolds on the car because the design of the stock manifolds actually flow very well and I used the stock catalytic converters because actually most all catalytic converters flow just about the same. Both pipes go over the axle on the passangers side. I use two MagnaFlow, straight throuth design, noise cancelling mufflers, (one on each side of the rear tub). The sound is not loud at all. However, it does have that deep, throuty, muscle car tone. In side the car, there is no roar, no rumble. Actually, the sound inside the car is just as quiet as it was with the SLP installed Loudmouth exhaust system that came on the car. The dyno test I did before and after the dual installation showed a true 5 percent horsepower increase with the dual installation. That was about a 15 horsepower increase. Other than the dual exhaust system, my Camaro is Stock. A true dual exhaust system is the only exhaust system that is worth the time and money to put on any car. Especially a Camaro or Firebird with an LS-1 engine. A great engine like the LS-1 needs to breath deeply to give out what it has to give and a dual exhaust system helps it do its job better.

 

If you like it loud like me, you will want it dumped at the axle, and run bullits. Clearance is tightest under the driver seat not the tunnel. If its done right you can run 3" and go over fairly large speed bumps slowly and not hit. I have 3" and have no scratches on them after many many miles, but I took my time welding them and they tuck up tight. There is alot of guys that like the sweet thunder muffs though and you might check them out too, but they dont flow as well, Its up to you what you want. To each their own.

 

pacesetters w/ 3in X into spintechs dumped before the axle on the TA. Loud and awesome IMHO (my neighbors just love it ) but ground clearance is a bit of an issue

 

thx again guys for all the feedback. I'm definetly gonna put it to use

 

another question I just came up with that I didn't find in the stickies was about where to put mufflers. before or after x-pipe? I believe tsp has their rummblers before the x. But I was thinking that it would be better to have them after the x so that the flow is already evened out.

 

The tsp true x rumbler is after the x...look where their dumps are man

 

What system is that? and is it for ls1 or Lt1

 

I've had 2 different dual setups on my car. Headers with duals dumped, then I had my duals ran out the Back. The first setup had an incredible sound, but there was some drone in the car. The second, relatively loud, and the sound quality went down some. I have Jet Hot long tubes, no cats, x-pipe, and single chamber flows. The addition of the tailpipes made the exhaust splatty sounding at 1/2 throttle, which I hate. However, it did eliminate most of the 1800-2000 rpm drone that single chambers are known for. I am going to reconifigure my exhaust so that I can run a dumped setup or have pipes out the back, and I'm changing my tips as well. The C6 tips I got will make it look a lot better. Ground clearance is decent with 2.5" pipe, I can almost fit a coke can under my mufflers, and it will fit under my x-pipe. I hope this information helps you. Oh, definately put your mufflers after your x-pipe. The x-pipe will have maximum effiency that way. Also, the way you position your turndowns will have an affect on the volume of the exhaust in the car. Here are some pictures of clearance and my duals both dumped and ran out the back.