Does anyone know what the diameter of the stock exhaust piping is?

Also, I was looking at MBEPIC and saw his 'dual exhaust' did he add another cat in there for both sides?

What kind of performance gain do you guys think can be had from a system of true duals over the stock/borla design?

Thanks.

 

Stock diameter size is 2.25". I think that is inside diameter if I remember correctly.

A free-flow converter was added to each side in place of muffler. Originally, I did not have that (just tail pipes with tips) but I found that the sound was too loud, not mellow enough. I took out about a foot long of pipe on each side and replaced with the converters. I emphasize free-flow because that is what they are. You can see right through from one end to other. It has some muffling or catalytic material that acts as a catalytic converter but it sure made a difference in mellowing the exhaust sound.

I have no idea about the specs on torque or horsepower increase but I can honestly say that there is an improvement especially in the top end (2nd, 3rd, 4th gears). I wish I was in a position that I could have dyno'd the car first and then after with the change but that didn't happen.

I now wish that the 1st gear was not so low because the torque/revs come on so fast that you need to go into 2nd gear in a flash. Other than that, I can't help you much further.
I don't know if others who have 6 spd manual feel this way, but I find myself starting out in 2nd a lot (not always but a lot).

 

So what piping did you use for your design, 2.5"? Also what type of converters did you go with? How much did the system cost?

Do you feel better having done custom over say a borla? I am debating about what to do with my exhaust system?

Thanks.

 

MBEPIC, I agree about the 0-12 +/- mph 1st gear, wish it had a bit different ratio. Perhaps 22 mph would be fine. It seems they intended the gear box for a rabbit chase until you hit third.

It really gets annoying in a stop / start environment.

As far as the Borla cat back system, I'm a little pissed at Borla as I ordered the system last week and they said it would be delivered today. Now Borla says it is on back order and they do not know when it will be available. Mind you, this was a pre-paid order from my parts dealer @ $649 and I only live a few miles from the Borla Factory... Needless to say, I went to my local muffler guy and said "F" it, order me a Magnaflow and weld the current tips on the new system.

IMO Borla can bite my *** and they just lost a new customer.

 

The new pipes are 2.25" to match factory pipes. I honestly can't remember the name of the converters but really it doesn't matter because they don't replace any other factory catalytic. The whole idea is to replace the factory muffler with something that will give you free-flow and a better sound. I could of cut the factory tips off and welded them to the new pipes but I decided to preserve the factory pipe and muffler/tips (stored away)and I like the round, aggressive look.
The cost was equivalent to about $400. U.S. but the biggest part of that was the custom pipe work. The exhaust fellow worked on the system three separate times only because I didn't have the tips during my first visit and then after the second visit to weld tips on and try that set-up, I decided to add the free-flow converters to mellow the sound (3rd visit).
This cost me a little more money in labor than it could have if I knew exactly what the sound would be like beforehand.

It is difficult to describe affect it had on torque because no measurements were taken but I can say that I notice very little difference in bottom end performance but certainly the engine seems to open up more in the top end gears.

We have a very strict emissions test in Ontario that must be done every two years after the vehicle is two or more years old. I should not have any problem whatsoever because I have not touched factory converters, sensors and in fact if anything the vehicle should be more emissions free because of the additional converters. The muffler doesn't do anything but add a lot of weight and muffle sound.

 

i would think that cutting the exhaust right before they collect into one and finish out with dual all the way out would help power...question is does the exhaust go from two 2.25" into one 2.25" then into the muffler? that makes no since.

 

It's 2.25" oval pipe for most of the system, and yes it does Y into the same diameter or 2.5" if I remember correctly.

As far as increased HP, no idea, but I'll definitely agree it pulls so much harder on the top end. Kinda wish we had 500 more rpms.

 

that's sooo restrictive....hmmm I need to experiment on a dyno...get back to you on this.

 

Mbepic's car is a TRUE dual exhaust. I might add that it sounds awesome!!

I full well plan to go the same route.

To hear this exhaust follow the link!

http://youtube.com/watch?v=l2qOUa5iOnc

 

Mine is also a full dual exhaust 2.5" all the way back to dual in/out muffler.

 

The exhaust is FULL dual exhaust...no stock muffler or other muffler whatsoever.
Originally, I used free flow converters but that was a big mistake...converters are meant to function much closer near the engine where heat is very high. In my original set-up, the converters degraded and eventually plugged.

I replaced those converters with stainless steel resonators and new stainless oval tips that are slightly angle cut. The look is much better...the over-all quality is much better and the sound is as good. The factory CATS are untouched and I have kept my original factory pipe and muffler/rectangle tips in case I sell the car and the buyer wants it back to original specs.

I am now going to investigate an 'X' Cross-over pipe, to scavenge the exhaust better and I believe retain some of the original low-end torque that I may have lost with this conversion. I believe I have definitely increased high-end performance and improved fuel mileage over factory specs.

If anyone wants the part numbers and pics of my latest exhaust set-up, send me an email at: mbepic@gmail.com

I have just come back from the Mosport, Ontario ALMS races and my Xfire sound would be right at home there, however, I was in a much quieter '88 Corvette.

 

Should have taken the Crossfire!

 

I suppose I would have but General Motors, Corvette Racing put on a Hospitality Lunch and Corral (over 100 Corvettes); they also actually gave us three parade laps of the track and if you timed it right with the car in front, you could do some nice fast cornering.

 

Email sent!

 

Ooohhh alright...I suppose if you put it that way!

 

Hello everyone I have learned a lot on this website about my car thanks to everyone out there. I have a muffler shop and I haven't touched my exhaust yet, lol. I really like quiet, but my magnaflo true X will be in today, and I'm going to put in place of the 2 rear cats. They do help a lot to savage the exhaust, now I might have a problem getting the full benefit from it with the 2 mufflers, but it sure won't hurt. Now I just need to know where to buy a Sprint booster???

 

Ok got the X on sounds good and quiet still, but I haven't drove it yet, I will get some pictures up tomorrow.

 

Well sorry I haven't got any pics. up yet, but I can tell you that it really made a difference in the sound. It gave it a really nice growl when you stand on it, but still plenty quiet while cruising. Still not sure on what to do out the back, I really want to get rid of those ugly tips, just hate to cut them off of the original muffler. So I might try a single in dual out polished Magnaflow and a pair of 4" double wall tips, I know it will look better just don't want it to loud.

 

Ok here are my pics...

 

And here are some more...