exaust question

bumpskier45

Registered User
just purchased my second supercoupe this one is a manual transmission,my first was an automatic. Anyway I went in to have the exause done and the shop was able to run true dual exaust with 2 and a quater inch pipe,with high performance cats,and dynomax turbo mufflers,so my question is this,the car actually doesn't sound as good as it did with stock stuff on it,and it feels like it has less power than it did with the stock items,now that i freed up some of my back pressure i wonder if that's why,anyone want to weigh in on this please. thanks
 
just purchased my second supercoupe this one is a manual transmission,my first was an automatic. Anyway I went in to have the exause done and the shop was able to run true dual exaust with 2 and a quater inch pipe,with high performance cats,and dynomax turbo mufflers,so my question is this,the car actually doesn't sound as good as it did with stock stuff on it,and it feels like it has less power than it did with the stock items,now that i freed up some of my back pressure i wonder if that's why,anyone want to weigh in on this please. thanks

"True dual" - that may be part of it.

These cars really want an X pipe to help the scavaging.

RwP
 
so no one runs dual exaust with sc's? I took the plan from magnum powers suggestion,and showed what the popular way to run these cars was,and he said why don't you just run dual exaust,which sounded ok to me i did it on a camero i had and it worked awsome,not sure what you mean by scavenger either,so what should i do now have them go from the cats to a 3 and a half inch then split back to 2 and a half inch just before the mufflers?
 
Basically true dual is higher pitched and a little raspier than the 3.5" split...most people like the deeper sound of a 3.5" split

You probably lost too much back pressure so a pulley would probably help that issue

Anyway make sure you keep a resonator or muffler in place of the stock resonator or you will regret it

Also exhaust is the biggest thread maker on this forum and all these issues have been addressed in the past

Good luck
 
I have true dual as well and love it but I also have cam heads and headers so it has a pretty aggressive sound to it
 
2 1/4 exhaust is kind of on the small side and shouldn't of affected performance negatively torque wise down low. An x or h pipe installed will help with the sound. An H probably sounding better. Scavenging on our motors I dont believe works out so well with our motor firing order. Also being supercharged not so much

If you didnt install an x or an h do so....If you dont like the sound a resonator will take care of the sound issue

Anythng else done to the car?
 
I only knew one other person with 2 1/4 dual exhaust and it had a nice rumble at idle...AWFULL when high RPM...No cats and flowmasters. Smaller pipe gives a higher pitched sound
 
so no one runs dual exaust with sc's? I took the plan from magnum powers suggestion,and showed what the popular way to run these cars was,and he said why don't you just run dual exaust,which sounded ok to me i did it on a camero i had and it worked awsome,not sure what you mean by scavenger either,so what should i do now have them go from the cats to a 3 and a half inch then split back to 2 and a half inch just before the mufflers?

Oh, a lot of folks run dual exhausts.

But a "true dual" would have no X-pipe or H-pipe.

For maximum benefit, you DO need an X pipe - which makes it not true dual, but dual none-the-less.

Scavaging - it's what some folks miscall "back pressure". It's where, say, cylinder 2's exhaust gas helps to suck more out of cylinder 3 due to the venturi effect of the gas moving. You can do a Google on "exhaust scavaging".

For the exhaust - you can get the pipes from Mandrel Exhaust Systems and they have the front and back halfs. What they don't have are the rear mufflers, although they can sell those to you also.

RwP
 
Lots of good information here,and yes it sounded awsome when it idle's but when you rev it up it sounds like crap imo. I was on the phone today for allmost an hour talking about the issue with xr7-dave,a dual in dual out resinater was what he suggested,the gases need to be put together at some point he had mentioned.whoever had asked me what else I have done to the car,nothing but the exaust so far.
 
I agree with Dave, just get a borla dual in dual out resonator and be done with it. Your exhaust sounds like crap because u lack that resonator. I've played with and paid the price for several exhaust setups. It's kinda pointless just to have an car that sounds good at idle. Also make sure your resonator "body" is atleast 18 inches excluding the tips, that'll helpout with sound.
 
the biggest one magnaflow makes which is the part number dave gave me was a 14",this exaust shop guy tried to tell me of all the muscle cars he has done over his 30 years in the bussiness,and putting that resinator on this car was pointless and would reduce power,this isn't a muscle car...its better its a supercoupe,and um im going to do what dave says 100% of the time.
 
magnaflow resonator

Dave is certainly one of the most called on experts on this forum of vast knowledge. I just wanna address a couple of things. Magnaflow does make an bigger resonator than 14 inches...trust me I have one on my car. The body of mine is 18 inches excluding the tips. The reason I recommend borla was because people have had issues with Magnaflow burning out, Dave can also confirm this. Also your exhaust shop guy is probably right he has never seen a muscle car with resonators. That's because "muscle cars" are mostly v8's and sound great naturally. Mufflers, no mufflers, x pipe, h pipe, etc. American v8's are in a world of their own. Know our motors will never sound as good especially with our firing order. Supercoupes are more of luxury sport class, we're the ones turning them into "muscle cars" so to speak. So without a decent resonator u get alot of rasp beyond idle. Turbo style mufflers usually sound more mello and deeper. If you want to see my resonator there's pictures of it in my supercoupe rebuild journey thread. Hell there's pictures of my whole exhaust before I put it on and afterwards.
 
Ive had exhausts with resonator removed that didnt sound awfull. An issue with this particular exhaust is that its 2 1/4 inch. That gives it a much higher pitched sound. A resonator would help but you can try an x or h in the exhaust beforehand..But cant garuntee good results. The resonator will ultimately help the most.
 
What year is the car to have duals put on it? Have the updated fuel tank on it?.?. From what I have read the answer would be no unless it's a late enough model.
 
I am going from a sound standpoint only. SC's do not lend temselves to exhaust scavenging so the benifit headers in that regard or h/x pipe I couldnt tell you.

From a sound standpoint an h pipe will yeild a deeper tone then an x pipe.

Performance wise on a v8 at least, an H pipe will give you extra power only at a predetermined RPM whereas an x pipe works at all rpm's. Im not sure how helpfull one is on a supercharged car let alone one with our firing order. Perhaps someone else can add to that..But it definitely helps in improving sound quality.

One of the sweetest sounding exhsuts Ive had on an SC was headers, high flow cats a single flowmaster as a resonator and two dynomax turbos out back. I bought the car that way and it sounded sweet. It was originally true dual and the flowmaster was added at soem point later on.

So you can add an x to your existing exhaust or an H. If adding an H Id spray down the pipes with paint, go for a full rpm pass through all gears then shut down. Wherever the paint burns thata where you put your H.

Most dual in dual out resonators are rreally preforated x piped with sound dedening insulation.
 
I should note that the reason why the pipe is two and a quater inch pipe is because that is what the manifold size is,I had asked the exaust guy to go back with two and a half inch pipe,he said he couldn't do that,it had to be whatever the size of the manifold was. I did purchase the 14" one from summit racing,I think I will like it the raspyness I get is mild so I think the 14" will be fine sound wise.
 
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