Putting 3" on van tomorrow, tips/suggestions?

[Revdoc]

Planning on doing a full 3" exhaust on the mini tomorrow. No muffler, no cat. Just 3" pipe. I have all the 3" mandrel bends that I'll need, just need to pick up some straight 3" pipe somewhere. I have a couple of questions, though.

How can I get the 2.5" swingvalve to match up to 3" pipe? I know I can cut the 2.5" off the swingvalve and weld 3" to it, but that seems a bit difficult and maybe unnecessary with a mitsu turbo? I can buy an adaptor, 2.5" -> 3" I'm sure at most muffler shops, would I really notice the lack of performance from using a 2.5" swingvalve?

Also, I see a lot of people running side exit exhaust on their minis. Is 3" no cat no muffler going to be too loud to run side exit? I used to run a Z28 with long tube headers, no cat and a hooker muffler, it wasn't too loud.

I've also heard of boost creep using 3" on a mitsu. I plan on upgrading eventually, so I want to do 3" now instead of 2.5" now and redoing it later. Will I experience boost creep? Even with a G-valve boost controller? Any easy fix for it?

Thanks,
Josh

[turbovanman]

I expanded my 2.5 DP with an exhaust expander then welded it to my 3 inch pipe. As for loud, yeah, I would think a side exit setup would be very loud with no cat or muffler. I am running a cat and muffler and its still fairly loud!

[russ jerome]

Drove my van for a week with 3" exhaust no cat/muffler. Only did it because of world record motor swap on a sunday but would not suggest it. Realy hard to sneak up on victoms with the constant whistle of turbo thru resonance of exhaust. Dynomax is strait thru and makes it a LOT quieter.

[Revdoc]

Well, it's done. 3" mandrel bent, exits in front of the passenger side rear tire. No muffler or cat. Yes, it is very loud. I can finally hear the turbo whistle. Later I will most likely add a dynomax bullet muffler or something similar.

[My96z]

How was the power increase? Do you get the boost creep? I bet that thing boosts like a mofo!

I am in the same predicament you were in: want to go 3" and plan tp upgrade but scared of the side effects with the temporary mitsu turbo.


Jeff

[Revdoc]

Well, power increase seemed nice but by that time, I noticed the boost was at 15 psi! Which caused it to hit the boost cutout, which scared the crap out of me and made me think I'd lost a piston. It skipped a tooth on the timing belt also, so I took it apart yesterday to fix that, and it's currently under the knife. So I'll let you know the real power increase when it's running properly.

Also, it does overboost very badly! I had mine set to a perfect 12 psi, and the first time I punched it on the highway it went right past 12 and on to 15. Very bad idea without an intercooler. So you kinda have to keep your foot out of it, it still creeps on me with the grainger set at 9 psi, I'm going to try lowering it later. The real solution will come about via the volvo intercooler in the backseat, as soon as it's on I'll just run whatever the mitsu can put out!