So I wanna get rid of my 2 pre cats I know the 99 4.0 don't have them my 02 4.0 does. Not sure if it will run rough or not anyone know if it will run rough or not. I'm gonna try it tomorrow

 

???

Cats and mufflers have nothing to do with engine operation

Cats clean up the exhaust, mufflers keep the noise down

You may get a CEL(check engine light) because emissions are not as clean, but if you have at least one Cat working that may not happen
But in either case engine operation would not be effected...........unless you plug up the exhaust

 

Just a heads up, if you do this on a 2002 ranger 2.3 i can assure you a drop in mpg, i had to retune my pcm and modify what the computer looks for