use the lightest flywheel, really makes a noticeable improvement in acceleration light crank pulley will help too. I don't even have double valve springs and the engine is really responsive ( spools quick ) and I never go over 6250 rpm ( soft rev limiter )

I'd go with roller rockers in any case where you have $$ as it reduces valve train friction and makes more power go to the wheels.

the A15 isn't a rev monster, but you won't need to rev it as much. Having a lighter valve train makes downshifting more fun.