i believe the stock turbo is a t3 and its rated at 250 i think. definetly go RB if u want ultimate potential. probably cheaper to go sr20 but the newer sr20's are more expensive. rb26 can go in too but u need an rb25 tranny and rb25 oil pan cuz the rb26 pan would hang too low on a 240. call shaun at upgrade performance (www.upgradeperformance.com) he's done rb25's before and i think he was quoting 5500 out the door for a swap. id say rb all the way. good luck with whatever u choose.