Haha here is a video to settle the debate, F vs 2J.
http://www.youtube.com/watch?v=EHIQ5umsn7w
Thats the fastest s2k so far, so far they are blowing away "RAW's" 2js2k car.
The SR in the s2k is a downgrade, stock F has been known to handle 700whp. You cant really argue with forged pistons factory, not to mention the motor flows way more than the SR will. Driveline is your weak link with the oem s2k stuff.