I know the preheaters on the '80-'96 F-150's have been known to plug up after awhile. In order to maintain "smogibility", do I need to replace the first cat. or preheater with a special kind of cat. or will any high flow cat. do? Once upon a time, a guy that owns a muffler shop told me I could eliminate the first cat. entirely and replace it with a nice y-pipe to the second cat. and it would be smog legal. Upon further investigation, I was informed by a local smog shop that this setup would not be smog legal. Any ways, I need to get my annoying exhaust leak fixed and I figured while I'm at the exhaust shop, might as well look into improving my exhaust setup. Any suggestions/info would be appreciated as always.

 

You can replace both cats with a dual-in highflow cat where the pre-heater is. That's what I plan on doing when I redo my exhaust. I think Sprocket had one put on his truck.

 

I know Sprocket is a fellow Californian so he has the same laws to put with as I do so I'll have to check out his setup. Thanks for the advice.

 

I don't think its quite California legal... he drove to Vegas to get it done