[wanab5150]

I certainly understand the quieter pipes and if I had not heard the 3 inch mufflers and found out how much HP is lost because of, in my opinion poor set up, then I would have been happy. Fortunately or unfortunately, I did find out!

I went the extra mile for the Roush 427R and assumed the superformance dealer would provide a correct set up for the engine they recommended to me.

I paid extra for a bunch of options such as the 17" wheels, non standard color choice, seat modification, and more. I would have sprung for a correct complete exhaust system if I had an inkling it didn't match up to the Roush motor.

If I only wanted 400 HP, I would have just put the Roush 347 inch motor in it and saved a bunch of money. Even the 347 makes 450 HP.

As far as the headers go, the heads on a 402 have smaller intake runners and intake valves. I can't imagine the exhaust port would be the same on both heads....what would be the use? larger intake runners and valves require larger exhaust ports and headers unless you want all torque and no top end HP.

If what you say is true, I still need a larger header. I would feel a little better if I knew I had a header more set up for my engine like yours. I might even pass on larger headers if the size difference in relatively small. Still investigating!