I am in the process of rebuilding and installing a 351m into My 1982 F150 Stepside. The orginal eng was 4.9L (see My Gallery)The 351m will have headers. I will be putting a legal exh system on. It will include 2 cats and mufflers. My question is: When I install the cats to the headers is there a min distance from the collector to the cat and Min distance between cat and muffler? I will be using flowmasters. Thanks Art

 

Well look at this way: The farther back you get in the exhaust pipe, the cooler and denser the air is. This means that the air takes less space to flow through. So if you put your cats farther back, it'll flow easier. Hope that answers the question.

 

The cats need heat to work. I say put them where ever they'll fit and as close to the engine as possible. Use 2 1/2" tubing to keep the flow up.

 

>The cats need heat to work.

Who cares if they work? As long as they're on there to pass inspection, who cares?