Depending on how much overlap and lift you run and how well dialed in the cams are makes a big difference. I ran a stock jdm bigport with 270 degree cams and it ran terribly until I played around with adjustable cam gears, after it was all set up properly it went heaps better than before they went in. These were cams designed with running the stock ecu in mind however, so the specs may be a bit different to the typical hks or toda etc cam grinds. Definately good bang for buck if you're going to fit them yourself.