1994 MR2

Custom Stainless Exhaust System

One of the first performance modifications I decided on for my MR2 Turbo was to install a high-performance exhaust system. I had several desired attributes for my exhaust system that I have listed here in order of priority: 

Of all of the systems available for the MR2 Turbo, the one that I liked the best was the GReddy/Trust Power Extreme. However, in addition to availability problems, I identified several things that I did not like about the Power Extreme: 

I was willing to try the Power Extreme anyway, but they were not currently obtainable. I finally decided to make my own exhaust system. I am now very glad that I was not able to get the PE system because my custom exhaust system has turned out to be much nicer and it meets all of my design goals. In addition, I ended up with these additional benefits: 

Due to the removable tip design, I can change the tips if I get tired of the current ones. I designed the system this way because I thought the large tips may be too radical. I had originally intended to make two sets of tips, but I actually am very happy with the first set and I doubt that I will ever want to change them.

Borla XR1 3-inch stainless muffler

Stainless 3-inch diameter, 3-inch radius mandrel bends

Rolled-edge, angle-cut, stainless steel tip

RMS B-pipe

Here is a list of the materials that I had to collect to build this exhaust system 

Finding and procuring all of these parts was a pretty big job in itself. Using the RMS B-pipe was a tremendous time-saver. Thanks Jeff!

Shortening the muffler inlets and outlets

I had limited experience TIG welding stainless steel, so I began by making a few preliminary cuts on the L-bends and then chopping up and welding some of the scraps until I was happy with the results.

First cut on splitter half

Second cut on splitter half

Tack-welded splitter

Finish-welded splitter

One of the more tricky parts to fabricate was the splitter that diverts the exhaust flow from the B-pipe to the two mufflers. I tried hard to make this part symmetrical with a straight inlet to equalize flow through the two mufflers, and therefore minimize back pressure. Due to space constraints the splitter had to be less than four inches in overall width. I decided to grind and smooth the weld on the splitter, so it looks like it was molded from a single piece of stainless steel.

In order to enable installing the long, gradually-tapering tips, the mufflers had to be installed parallel to each other and toward the front of the exhaust system compartment, so that the outlets would be as far forward as possible. This has the added benefit of making room for a trunk-mount intercooler duct.

The car sounds much more throaty and deeper with the exhaust system. It is significantly louder than stock, of course, even at idle. But it is not as loud as a straight pipe and it is totally tolerable. In fact, to me it sounds much better than stock, which in my opinion is too quiet for a serious sports car! The reduced back pressure enables the turbo to make one more pound of boost (10 PSI as opposed to the 9 PSI it got stock). Between the extra boost and the reduced restriction, it should be making a little more power, but I don't know how much.

Cost breakdown: Several people have asked about the cost of this system. Don't plan on saving money with a system like this one! There are not many systems on the market that cost as much as this one did, and that doesn't even include labor!

Sound recordings

Read some of the comments that I've gotten on this exhaust system!

sweet exhaust any idea what kind of money you have into that?

Very, very well done! I have a black 93t with a Rebel Motorsports dual exit straight pipe, using tips very similar to yours. Mine are 4", slant cut, rolled edge. I chose them for the same reasons you chose yours. Where, might I ask, did you find your tips? If I ever get tired of my straight pipe (haha never), I may need to find these puppies and duplicate your exhaust!

That system is just BEAUTIFUL! How much did it cost to build?

nice job! but i think ur comments r right ... it is kinda expensive, but then again u have 2 mufflers, not 1 ... y did u decide on 2 instead of 1 muffler? i can see all the cost savings u can get ... could u have fit the mufflers at an angle rather than at 90 deg angles like u have now? there might be extra hp's to be weened if u do that. *shrug*

Nice work on the exhaust.  I plan on doing something similar without the mufflers.. more like the RMS..  Where did you get the tight radius 90's.. could only find 6" radius ones.  

I think your exhaust looks great! I have the DESP right now and except for the time at autocrosses it's a little loud for me. As a matter of fact, I just received a ticket for "running a straight exhaust" on my car. I have been looking for an alternative and the idea also crossed my mind to used a Borla XR-1 racing muffler. I thought about just using one (less expensive) and coming straight off of the RMS B-pipe and out the left or right side.

Which XR-1's are you using? I thought about the 12" with as little bends as possible and perhaps angling the output of the muffler without a tip. Since you've actually seen the mufflers, do you think the tip already on the muffler would extend long enough to pass an inspection?

Anyway, good job on your system... it really looks good.

Damm that exhaust is nice. I sure like nice trick looking equipment. Did you do the welding your self?

Your exhaust system for the MR2 looks pretty cool

Your car is awesome and your exhaust is beautiful in planning and execution.

I've been meaning to comment on your exhaust for quite some time now. I lost the address to your website but after some unrelated browsing, I ran into it again. So before I lose the address again, let me say that you've got one awesome looking exhaust there. I remember a few months back when you first finished the fabrication; I was amazed that the finished product was completed without having to make one trip to a muffler shop....very nice craftsmanship and quality that rivals those $1500 exhausts on the market for the MR2T.

I want you to make one of those systems for my MR2, its a 93 MR2 turbo, please tell me the price and how long it would take. I want it to be exactly the same as the one you made for your 94, thanks Bryan. Can you make me a recording of what it sounds like?

Your exhaust is BADASS

I wish I could buy this exhaust I could have a couple months ago but I spent my money on other mods. If you could mass produce these you could make tons of money this is the best looking exhaust by far I have seen. It sounds great too. If you ever make any more e-mail me. I would be very interested in buying one.

Speed-Wiz automotive analysis, design, and simulation software