I hit a speed bump hard and punctured a hole in my Borla proxs muffler about a month ago. It is mounted where the stock main cat would be (on a 87 TII), with straight piping running out the back.

Now I ordered a new Magnaflow (oval, 3" in center, to 3" out offset).

I was going to run this in the same location, or else in the back where the stock mufflers go. Which would be more ideal?

Also, I ditched my aftermarket hi-flow cat (3") a few months ago, but I've been running into fuel cut in the cold weather. (even with my ported wastegate)

Should I have the hi-flow cat reinstalled? I must mention, I have most of my emissions equipment removed (air pump included).

Tell me what you think.

 

Will a hi-flow cat melt with no air pipe?

 

It will clog, yes.

 

I have a flowmaster super 40 in place of the stock cat, sounds great and quietens the exhaust. Magnaflow is just as good, stainless is a plus. I'd put the magnaflow back where the borla was, it works as a presilencer.

I dont know about the cat clogging with no air pump, my 89 S10 has no air pump and still has a cat. then agian it's not a rotory. It definatly wont melt, the core is ceramic and the case is stainless, mucho heat resistant.

-E

 

You must have hit something pretty nasty to rupture the muffler like that, either that or it was hanging super low?

 

Yeah, it was in place of the stock cat, so it was too low. A speed bump finally ate it.

I now have a RB full downpipe (3.xx") to 3" into the single magnaflow in the rear pass. side. It it SUPER quiet, even at 7K.
The only problem is boost creep in this cold (40-50F)weather. I'm talking about hitting fuel cut in 2nd gear.

I thought about having the hi-flow cat there to limit output a little, or else going with a seperate wastegate pipe. (External dump, or back into the exhaust)