Thanks for all the advise guys

As for a YB 16v head, I'ed love one... but I've given up looking, I cant find one without paying a daft price. Been looking on ebay/gumtree/forums for over a year and they are either over skimmed and have no life left in them or there tripple the price its going to cost to build a pinto turbo.

Would a T3 not be on its edge, if I'm running 300-305bhp? Trying to get my head around turbo's at the moment, is a .48 exhaust housing only found on a T3?

I asume a .48 exhaust housing would be suitable to run 300bhp but have qwick spool. The next size up .50? would handel 300 but have a longer spool time?

I dont know if its correct but a friend at work has told me T3's come in two sizes, a T34 is the large T3 exhaust housing (.48) with a T4 compressor, then a T4 is a larger exhaust housing with the same compressor as the T34.