Hi. 1st of all LJ_GQV's car made 300bhp with intercooler, remap, exhaust and intake...this has been proven.
My car has been running 285bhp since last remap/exhaust and intake, I now have Novitec powerjet 3 with octane booster and it feels stronger than remap - will see in two weeks time when we have an Alfa dyno day in SA.
I've had Water Meth installed on my GQV for nigh on 30mins...I didn't like the buzz the pump was making in the boot. I removed it, but without a tune the intake pipe to throttle was as cold as ice and the car held boost very well, so its not really a must but a nice to have in my opinion for anything under 300bhp...if you go over then do it.
A GQV has been fitted with a larger turbo by E-Tuners, read all about it here
...this car runs 340 wheel horse power!
They changed to a larger turbo, some clever software, intercooler and exhaust and there you have 340whp!!!
It seems you really like the 159, so get a GQV k04 turbo, piping(is throttle body same size?) and then do ECU tuning...assuming ECU is the same? And proper mapping by someone that knows how to get past the MED17's built in parameters or what does one call those things? Limiters?
Having played around with software and Novitec, the software requires a specialist in the MED17 to know what their doing, LJ_GQV's ProAlfa knew what they were doing, so too does the E-Tuners guys who can raise rev limiters, include a launch control etc all in the standard MED17 Ecu...I think this car also has its electronic traction control removed when in D or something like that, contact the guys wat E-Tuners who did that big turbo conversion and go big all out, rather than force a GQV to 300hp...
Good luck and keep us posted!!!