For now my mx-3 has a 1.8 v6 motor. If I want to replace the engine to 2.5 klze v6 engine, will i need to replace the gearbox also? would it be fine to install the 2.5 klze into a 1.8 v6's gearbox? thanks

 

mx-3.com has lots of info on this swap u dont have to change the tranny as the klze will bolt up but a mx6 or probegt tranny would have wider gears and be stronger the mx6 havin the widest of the gears- y not buy a klde (probe gt, mx6 motor) for around 400 pay 150 klze intake manifold and 150 klze cams pheno spacers and get the mx6 tranny get ur stock gs flywheel shaved and use it with the new motor as its lighter (better acceleration, throttle response) and put a new timing belt and water pump in. all this would cost the same as a ze and be the same cost to install as it bolts in. u should change the vaf and ecu definatly with the swap., ud be left with a frankenstein motor like a ls/vtec but it would still be more reliable than the ze as u would of just saved a expense or labour intensive job for urself by alreaddy changing the timing belt water pump. in a mx3 that would haul a-- be in the 14's for sure with a upgraded clutch which u would have to do ne ways with a klze plus the klde bottom end is better for boostin or sprayin than the ze without upgrading internals. check out probetalk.com or mx-6.com for more info on the bigger brothers to the k8