[vtirocz]

Originally Posted by parish8

here is what holly is claiming with their crush pipe delete kit.

I would expect the crimped section to have a significantly higher impact on performance at high flow conditions compared to low flow conditions. The dyno chart shows a similar delta at low speeds (lower flow) and high speeds (higher flow). Whatever caused that delta was likely not the crimped sections.

Mishimoto already ran a back to back test showing transparency between the crimp and full tube in that section of the exhaust:

https://www.mishimoto.com/engineerin...he-crimp-myth/


The crimp definitely reduces cross sectional area (significantly), but is so far downstream from the combustion chamber that the exhaust gas has cooled substantially and does not cause much impact on the torque curve of an otherwise stock car. As HP levels (and exhaust flow) increase, I'd expect that could be a bigger factor. For similar reasons, the stock SS exhaust produces about the same torque/power curve as the optional NPP exhaust.