Well i'm assuming the K20 swap is a K20A3 Coming from an Acura RSX or EP Civic Si correct? Top end would technically not change, since the top speed is programmed into the engines computer, but the Q.M. estimate? I'm gonna say...15's, maybe 14's if you've got good parts. Now, if the K20 is a K20A JDM engine, then you have way more power to deal with.