what the heck? I can feel a considerable loss around 43 to 4500 rpms. Can anyone help? Here are my performance mods if this helps, y-pipe, injen cai, cm straight pipe, nismo grounding kit, and unorthodox UDP. any help would be great.

 

ur vi is broken

 

Have someone stand in front of your car with the hood open. Stomp on the gas taking the tach up to or above 5000 rpm. Have the person in front of your car check to make sure the actuator arm on the intake manifold moves. That is a start atleast.

 

possible MAF failur too, do you have a SES light?

 

I was thinking something with the VI, and no my SES light is not on. Anything else like maybee cleaning my MAF, or new plugs or i dont know. Thanks for your help sofar guys. Anyone else have an opinion?

 

I posted for something similar yesterday, except mine's a subtle change around 3400. No SES. Suggestions were to clean the MAF, which I did, even though it was fine. The K&N was pretty nasty, so I recharged it. It seems a little better, but I'm sure the ECM is still relearning right now. I'm thinking about a plug change next. Good luck to you!

 

I had the same problem i cleaned the maf a little and felt a slight diff, went to clean the maf again and completely screwed it up, so i was forced to get a new one from the dealership. Paid the $80 and installed it @ the dealership myself best $80 bucks i ever spent on this car.