Exhaust system 1993 F150
 

I've been asked by someone who regularly reads over my shoulder to ask the following question:

He recently purchased a 1993 F150. It has a 305 engine in it. Underneath it looks like it has two catalytic converters going into dual pipes... was this stock or is it aftermarket?

Further, how would he do cat-back modifications? Do both converters remain in place? What is purpose of second converter.

Sorry - I really don't know much about this subect, so I figured I'd ask for input.

Thanks!!!

I'm assuming you are referring to a 5.0 (302) here....

I'm not sure what you mean by 2 cats going into two pipes....

The stock configuration was two pipes (one from each cylinder bank) into a pre-cat, which had dual inlets and a single outlet. This is followed by the cat, which was single in and single out. After this was a piece of flex pipe and the stock muffler, also single in/ single out.

Cat back systems are designed to bolt up to the stock cat and include the pipe between the cat and the muffler, a new muffler, and a new tailpipe (some cats back systems have a single in/dual out muffler, and will include dual tailpipes).

The first cat (dual inlet, single outlet) is actually a pre-cat, or cat heater. Basically, its job is to keep the exhaust superheated so that the catalyst can do its job (reduce NOx). A cat-back system is only designed to replace those componets located downstream of the cat, you'll keep the pre-cat and the cat, and only replace the pipe from the cat to the tailpipe...hence cat-back.

Hope this helps.