The exhaust manifold I chose you use is made by a company in Finland called Proturbo.  Originally, I had the exhaust manifold customized to fit my wastegate.  The pipe connecting it only came off of on of the runners, which was very poor flow.

    After about 9 months, I decided to upgrade my exhaust from 2.5" to 3".  This upgrade dramatically changed my power output.  It turned out my 2.5" was causing a LOT of backpressure when running over 7psi.  When I upgraded, not enough exhaust was flowing around the turbo, and ran into a situation called "overboost."  This means too much exhaust is flowing through the turbo, and causes the boost to not stop at a certain psi.  I blew a head gasket while this was going on, because I ran 21psi (whoops). 

    To cure this, I cut off the old wastegate adapter, and took some extra pieces of 1.75" exhaust pipe, and welded them to both of the exhaust manifold runners, so it would increase flow. This upgrade stopped the overboost, and kept the boost level to where I wanted it.

    The wastegate itself is a 35mm Turbonetics Deltagate  with a 7lb spring.  I have not had any problems with it.

    The downpipe starts off as 2.5" with a V-band flange that connects to the turbo. It then has a 2.5" to 3" transition, then a 3" 90 degree bend.  As it goes down, I put in a 3" flex pipe, so when the engine torques, it does not put any stress on the exhaust system or flanges.  At the end of the downpipe, I welded a oxygen sensor bung.

Downpipe and Exhaust System

   When I first turbocharged my car, I went with a 2.5" exhaust system, with a catalytic converter and a 2.5" mangaflow muffler.  Nine months later I wanted to upgrade, my catalytic converter was also clogged badly, so I decided to swap to a 3" exhaust.  My original exhaust cost me about $600 at a shop.  I did not want to do that again.

     For my new exhaust, I bought 2 3" mandrel U-bends, and about 8 feet of pipe.  I also bought a 3" in 3" out magnaflow muffler to keep it quiet.  I also learned how to weld so I did it all  myself, and saved a bunch of money.

     The trickiest part of this process was cutting and welding the bends to conform as close to the chassis as possible.  Since my car is already REALLY low, I could not afford to have a low exhaust system.  I welded it together piece by piece, so it was just perfect.  I retained all of the stock mounting points as well.  The welder I used was a basic Lincoln flux-core wire feed, nothing special, but the welds aren't that pretty (who cares anyway?).  It turned out well, and gave my car SOO much more power, I didn't expect it.  That, and my car was overboosting due to a bad wastegate adapter design on the exhaust manifold (cured that now.. look at the manifold page).

     Below are pictures of the new exhaust, differences in size, and the clogged catalytic converter.