KA-T is better than both, visit
KA-T.org - The Home of 1000+ whp/7 sec Turbo KA's and check out the flat, powerful torque curves on the dyno and see the video section for them in action. People make 300+ whp and even more torque on 12 psi all day long with a moderate sized turbo.
KA's also cheaper and more reliable (with the proper tuning) than a poorly maintained Japanese SR20 that hasn't been rebuilt. Really the only good thing about SR20's is all the fan boys that will be sucking your weiner and the rev limit. Other than that its a peaky motor that lacks torque. The only reason Nissan had it succeed the CA18DET is because it was cheaper to produce.
The fastest KA-T's are in the 7 second range. They have more displacement, a stronger block, more torque, and better gear ratios than SR20's.
YouTube - R@mon @ 15psi VS C6 z06 boltons
Street car KA-T vs. 550WHP Z06... Z06 gets beat and its not even a close race.