if the lag on the t25 pisses you off then dont bother going to a disco potato. they take alittle longer to spool up than a t25 (not THAT much longer) but gives a nice kick in the ass... 4000 MIGHT be enough to get you there if you can do everything yourself. and the motor doesnt need a rebuild. you wouldnt be able to keep it at a daily 300rwhp. the motor would die pretty quick with stock internals... and a rebuild with forgies will cost around the 4000..