i have a 96 f250 hd which i cut the cats and the mufflers off it was running true duels one cat and one thrush muffler each 2.5 inch pipe the whole way i cut the pipe right after the cab both pipes are right next to each other, i am now have a loud squeaking noise coming from the engine, heres the question can lack of back pressure do that because of all the air freely moving or could it be one of my pumps?

 

Please read, thanks.

https://www.f150forum.com/f11/exhaus...re-myth-78102/

 

Back pressure is not a myth, sorry.

 

^ Care to explain how backpressure contributes to proper engine function?