power upgrades

[911nutter]

having just read guy's gt2 antics, i'm wondering about power upgrades on my c4s.

is it wise? would such upgrades invalidate warranties? are there nasty side effects to having upgrades.... and what would you advise a maximum power upgrade to? i assume the car could take it seeing as it's basically a turbo bodies car with turbo brakes / wheels etc.

can anyone educate me on this?