I have a EF2 XR8 Manual, Well i noticed a litle bit of difference when put the K&N filter in. The major difference in performance and sound was, Pacemaker extractors with fac cats ( they were cut out to bigger diameter) and twin 2 1/2 custom bent exhaust. The sound is awesome. It doesnt drone and doesnt sound to metallic. Like some stainless steel jobs do.I also cut the front of the airbox out and replaced the harmonic tube on the inlet (that kidney shaped thing) , with a nylon plug that i machined up. Its not a real fast car but i know there a few people in sydney with wip lash of the necks. Well i hope that helps. All up i spent about $1700.