engine problems
 

the car isnt running to its full potential right now. i dont know exactly what it is. it gets full boost from the turbo but the first 2000 rpms and 4500 is the only power im getting from it. it starts to rumble alot after that. does this mean i need a new engine. the engine was rebuilt 2000 miles ago. it has racing beat exhaust, intake and hks fuel cut off. let me know what you guys think.

You may need to tee in a mechanical boost gauge to see if you are hitting overboost fuel cut.