A guy up the road from me has over 250 bhp from a Meg F7R n/a. It's not road legal though. I think they reckon 270/280 is doable but they want to strengthen the internals more for the high revs hehe.
Cliolord had 234 catcams I think? They are a bit more extreme. I think what I use the car for I am happy with it as it is, though I might try a lightened flywheel or short ratio box as well this year.