PERRIN_Jeff

This was something we wrote up a couple months back to show our progress on our turboback exhaust. We have been so busy we forgot to post it! Its good timing anyway as it just means our production parts are that much closer to being done! The full writeup can be seen HERE on our site...

EVO X Turboback Exhaust Build............


We have had the X for a few weeks, and in that amount of time, we have dynoed the car in stock form, and dynoed the car with a custom hardwired Unichip. Both have proven to show very good HP numbers, and this is with the stock exhaust, intake and other parts! Like our other builds we have done, we are building the parts for this car in the direction that we expect most customers to build their car. So after we were done with our ECU tuning, the first item we built is the Catback Exhaust.



The formula for the catback is simple. 3", Stainless steel, mandrel bends, and a free flowing muffler that is quiet. Using a similar design to the stock muffler, where the center inlet and dual outlets exit the sides, we started with the back of the car. With our basic muffler laid out and 4" tips in the back of our mind, we started...



The 3" center inlet muffler consists of a standard straight through type muffler, but with a center chamber that divides the exhaust pressure equally to both sides.







The look of the tips is very important as the OEM tips are horrible. They seem crooked, not quite the right shape, and not fitting of the back of the car. The STI at least provides tips that fit the back of the car. Its like Mitsu forgot about tips and made it a last minute decision. We went with 4" tips, and just for fun we bead blasted the tips to provide a dull silver finish. This may not be how the production tips look, but it does provide a very clean look.



The tips are lined up to match the fins at the back........



Please ignore the dirty car..........
With the catback exhaust done, the next part to replace is the catpipe. Like many other guys out there that would replace this with a catless pipe, we are not going to follow that path. Like we have been doing over the last few years is strive to make more legal parts for your cars. The catalyst on the New EVO not just one cat stuck between 2 flanges like the old catpipe. The new cat pipe has 2 bricks in it, and one 02 sensor. While it looks like it's just one, there are 2 cats in the same pipe.



Here you can see the 02 sensor wire harness/bracket...........

One, in front of the 02 sensor, and the second behind the 02 sensor. So in order to keep the system legal like our other parts, we had to make the cat pipe with 2 cats. I know everyone in the EVO world is saying there is no way that it will make power. We have been using the dual cat setups on the Subaru's for a while now, we have seen virtually ZERO effect on overall HP. Even on cars making 400WHP or more, 2 cats doesn't seem to be an issue. In the pics you can see the strange bracket that is bolted to the bottom of the pipe. This is the bracket that takes the 02 sensor wire from the passenger side of the car, to the driver's side where it plugs into the cat.



OEM vs. PERRIN Prototype, ours is lighter, neener neener neener............

Next up on the exhaust is the downpipe. This part was very hard to build on the car, so instead of fighting the tight spaces, I made fixture of the OEM part. In order to ensure the PERRIN downpipe wasn't going to hit any other parts on the car, i measured the OD of the OEM pipe and added room as though it was a 3" pipe.



Some assembly required...............



Close up of OEM part and the PERRIN 3" Downpipe......



Here you can see the studs for the heat sheild........

On the fixture I used some welding rods to mark the tight areas and the centerline of the pipe. I would show a pic of the fixture, but it was kind of ugly. All the extra work paid off, as the finished part fit perfect on the car and had no issues with clearance. Like the OEM part, we made sure to put the heat shields on the downpipe next to where it passes by the rear driveshaft output.



Looking up at the heat sheild.....



One more looking up toward the turbo..........

After all said and done, I was lifting all the pieces so many times, that I started to notice another great benefit, the weight. The stock system is small diameter 2.3" tubing, and full of heat shields, and a muffler with lots of chambers and sheet metal. Our system is 3" tubing with no shields, and a much simpler muffler. Anyway, our PERRIN Exhaust system saved 20lbs over stock and, our prototype system doesn't even have the lighter 18ga tubing (it has 16ga which is thicker).

OEM Downpipe weighs 5.15lbs where the PERRIN prototype is 4.5lbs
OEM Catpipe weighs 14.7lbs where the PERRIN prototype is 7.65lbs
OEM Catback weights 43.5lbs where the PERRIN prototype is 31.6lbs

So all these pics show the parts, we know it will make more power just bolting it on. But how much is the question. You will just have to wait and see! Within the next week we will provide results doing back to back dyno runs and further tuning with the UNICHIP.

Bighec

iTrader: (9)

Looks awesome! When might this be available.

ikuto

iTrader: (11)

Turning out really nice, will there be different exhaust tip options? Waiting on some sound/video clips on your Turboback .

PERRIN_Jeff

I figured that would be the first question!
In roughly 6 weeks or so. We just did some final beating at the track yesterday and everything held up great, muffler still sounds perfect, cat still works! Yes CAT, single, not plural. While the pics show 2 cats(just like the OEM part) we have gone with a single cat. What is funny, is on the dyno, with 2 cats or one, the power was EXACTLY the same... We removed it to be more price competitive on the whole system.

Sound clips are done, and should be on our YouTube sight. If not it will be tomorrow. At this point the tips we feel are best are the 4" round tips. The quad tip is cool, but too much for the holes. We will for sure offer this in our stealth black color.

But you have ideas on tips, give us your thoughts.

alan678

iTrader: (18)

quad tip....umm.....no

gizmotoy

I'm not a big fan of giant round tips, but that's pretty much all that's offered by any company at this point. I think you're right about the stock ovals, as they do always seem to look crooked. Not to bring up a competitor, but I think Cobb's quad-tip prototype catback looks great (and not over-large given the bumper cutouts), but we probably won't see that part for another year given their typical time to market.

If someone had a decent non-round or quad available, I'd probably be among the first in line.

DC_TypeR

iTrader: (10)

Any plans for a turbo outlet pipe?

danielskshin

iTrader: (4)

Now that's the way to make an exhaust. I also like how you guys are always thorough in your explanations.

ikuto

iTrader: (11)

I want to see Ti Tips, maybe you guys can make it look even better? I know you are going for stealth which I like too, but I also want to see it with Ti tips if possible.

PERRIN_Jeff

The round fits the back of the car pretty well which is why we did the 4"ers. But oval or something else is totally doable.

At first yes, then after seeing how short it was, then seeing how another vendor made one and it made no HP, we will not do it right away. Later on when we are less busy you may see it, but if it doesn't make HP, its going to be hard to sell.

Thanks!

Ti, that is something we thought about. The problem is cost. We build the exhaust in the US (not china where most Ti tips come from) So the cost may be a bit scary. But we will see. Good suggestion!

DC_TypeR

iTrader: (10)

Jeff,

I think there might be some confusion.

The turbo out let pipe - AKA o2 housing (which it isn't an o2 housing anymore, because there is no o2 sensor in it. This unit, according to vendors made power.

The Down Pipe, didn't make power "according to vendors"
I have a custom 3" down pipe, and it did actually make power.

Thanks,

Chris

PERRIN_Jeff

Here are a couple more pics from the back of the car.



It looks like our trailer is leaning way over, but its just an optical illusion. Its like one of those Escher Drawings..






These are the 4" Round tips, just at different angles.

Alexander

iTrader: (1)

sound clips please

PERRIN_Jeff

Hmm, i thought, AMS made one of these, and said it didn't make any power. This was even with the DP and housing in one piece. This was a while ago, so i could be mistaken. But on the note of the DP not making power, we did find more power from the catback than the catpipe and downpipe. The DP and Cat pipe helped low end power most.

DC_TypeR

iTrader: (10)

Jeff,

AMS didn't make any power (so they say) with the Down Pipe alone, they tried
2.5", 3", and 3.5" if I am not mistaken.

When they made the o2/downpipe combo though, they did make power, as the o2 pipe is very restrictive.

Buschur also notes that the biggest gain in the exhaust system, other then the catback, would be the o2 housing.

Please look into this, as I and a lot of others would be interested in purchasing .

Thanks,

Chris