Dude, would you not find that the weight of the zx is a real down feature of the car, jim_supra's dad has one, which is meant to be powerful, I have been in that and jim's NA and I can honestly say that I felt the Supra was swifter.
I do not know wether that was bias talking, but the Supra might feel faster due to it being about 300kg lighter.
My NA AUTO is putting out 231.8bhp, after basically a NUR-Spec and XERD Header. My intake system is lowering the power (IMHO) due to its volume, but will pay dividends when I get a turbo for it. But considering that stockers with similair mileage, etc. were pulling 204-208bhp.
At the end of the day Dee, your mate just has to take the acid test and try the car out, he might end up prefering the Supra, the ZX is a nice motor, just such a huge Ass!