My cat is clogged on my 88. 3.9L. Will it hurt to leave the CAT off. Can i run the pipes with out it.

 

Not likely to affect performance if it is gone, but it is illegal in most states to remove it.
Long time ago, I had one clogged, and I just broke out the innards using some rebar and a hammer.

 

thanks

 

Yup gutting it is much preferable to removal that way it looks like you still have a cat on there

 

Gutting and leaving it is the best bet, as said, in states with inspections/emissions tests. If that isn't a concern, cut it off and put your choice of exhaust on it. Either choice will improve the sound and make it run better, with more power and slightly better mpg.