After seeing a thread where an X member got pretty good gains changing cams. I was wondering what could be seen with a cams + retune using the stock RA turbo. Would the cams be inefficient as the turbo would be maxed out from other bolt-ons - IC, TBE?

 

not necessarily. they'll open up the breathing because upgraded cams can do two things: increase the duration the valves stay open, and increase the lift of the valve. with tuning, you can change throttle response and even where your powerband is. some people want to keep their factory turbo because of it's quick spool up, but it kind of dies up top. getting cams can broaden your powerband up top.

i had HKS 256 cams on the intake of my Silvia with 264 cams on the exhaust side. this brought my powerband up nearly 700 rpm! if i had reversed them, i'd have much more torque down low, but still lose wind up top. in retrospect, i could have got 264s in both intake and exhaust, but i got a great deal from someone selling them for only $300!

 

i would think so, its not so much psi but volume of air that the compressor is limited too