I have a 95 mustang with a 302, system max, and trick flow stage 1 cam, motor has cobra heads. Car has 373s in it. My problem is that when I got the car back from the builder it felt grear and would really pull when past 4k, well now it feels like it is pulling but not as hard and the blow off valve sounds different then before. I have checked all hoses, clamps, and pipes. Kind of lost?