2.5L engine has tons of potential however you wont be getting HUGE hp outa the engine. Yeah its got tons of displacement but its plagued with softa valvesprings and thin cylinder walls with badly placed valve rings.
1st thing to do is relocated the overly sensitive knock sensor to the firewall as it makes a HUUUUGE difference in performance, and its free.
headers are available
CAI intake (made by hotshot)
suspension
exhaust
ECU
a turbocharger is available which claims 250hp.. goto
www.nissanforums.com and search turbo in the qr25de engine section and youll see it.
its one sweet ride...