PJsXR8 has 3" single on his AU2 200Kw XR8. It dynoed at 155rwKw, only 5 short of an AU3 220Kw XR8 Rebel. He also replaced the headers with Pacemaker headers and went high flow cats, although I've been told the cats don't make a lot of difference as the standard cats are 2.5" and flow pretty well - and the pacemaker collector pipe is 2.5" anyway.
AU1 XR8 Auto 147.9 rwkw (approx 215 fwkw)
AU2 Wagon HAD Auto
17s, Pacemakers, 3" Intake & Pod filter (The Family Hack)
FPV-XR Club ACT