Leigh I have to tell you i love this European you. But if your wearing a carry over your shoulder it's over lol.

I remember reading 21st century performance and the head in a l series turbo setup will mean squat, only if Your chasing every last pony. Thats why the large volume u67 head or whatever it is will be best, will drop compression a tincy bit to stave off detonation and allow allite more boost that may increase chance of det.

Lags has had ca, a series turbo and atmo, sr and also involved in marks 180b l20 turbo setups plus more!!! I tend to agree with him but all a series turns seem to suffer ring failure of some sort (ask 1200rc lol )

Easiest option would efi the a15 then work out a low boost set up for it. Higher comp good off boost and low psi will give it a kick... Won't be a ca ball tester but enough fun for you hopefully.