I recently upgraded my turbo and dump/front from a bitza set up that started with a split dump on the standard turbo, then a front pipe added on later, it was good for 212kw but limited due to the 2 1/2" dump and the turbo at it's limit, mind you after 18 mths @ 16 psi it was still good, then at some stage I noticed it wouldnt boost above 15psi, Dan (3lit3 32) reckoned it was the studs snapped on the manifold, he was right but not quite as I had cracked the manifold as well. So I got a turbo with dump and a second manifold and installed the lot myself, and after a delay due to dyno comps, I had noticed that the cat was only 2 1/2" and with the bigger dump, the exhaust note quite louder as well, Right Price installed a 3" cat and resonator for 400 and I was off for a retune, it made 312rwhp/232kw @ 14psi easily, the turbo is a bit laggier but seems to be more gruntier down low, if that makes sense, the exhaust note is alot gruntier as well but the resonator took the harsh bark out of it. my next step will be the injectors, 550cc should do me.
A few more pics of the whole works are HERE
Nobody can identify this turbo, GoFastBits said it was probably a HKS prototype, it is a BB and has american threads in it, Dan reckoned it be equivalent to a high flow and Peter Woodward my tuner said it looked like one off a Rotary .