Just a larger TB isn't going to really gain you much. Actually it can hinder performance. You need to get the plenum where the TB bolts up enlarged to match, otherwise you have just negated what you did, and have created more turbulence because of the lip caused my the mismatching size.
moonwell, major work will be going in the 2.8l next year!
Higher compression pistons, performance cam, roller rockers, forged rods, higher flow injectors, extrude honed intake plenum and heads. Everything bassically to get it up to 200hp at the wheels. Even if I have to modify the plenum a bit, won't be much of a bother.
And will all that, I'll have to spend money to get a limited slid differential for the darn thing....
It doesnt take much to pert the upper intake plenom to 62mm. I think franz does it for like 40. He's making me a cai cheak out the forums if you want to see pics.And i think they dynoed the 62mm tb to put out something like 7 hp on a stock motor. Hope this helps.
I know this is old, but you should always check for vacuum before running out and buying a bigger TB. Otherwise, you might not even need a bigger one. Its like putting a 3" exhaust piping on a non turbo V6, unless you pushing like 400 hp, you dont need it that big.