I know you can "gut" the regular cat, i was wondering if its any different doing it to a hi-flow. Thanks...

 

Why pay money for a high flow and then gut it? Get a midpipe and run a restrictor plate if you're worried about creep. I have a midpipe with a restrictor plate and the Blitz SBC-iD and I can control my boost just fine. I have no fuel computer and the car runs like a champ.

 

just throwing out a couple of thoughts...if your hi-flow cat is good, why not just sell it...I bought a midpipe from a guy who sells on EBAY for a $100, fit and looks great... a good hi flo should easily sell for more than $100

 

Buy a midpipe and sell the high flow cat. You will come out ahead.

 

maybe he meant is there a difference between a gutted stock cat and a non-gutted high flow cat. If that is your question then the answer would be yes. The stock exh piping is smaller diameter and is quite restrictive compared to a 3" pipe even with a high flow cat.

 

Or maybe he's worried about getting stopped for not having a cat. In any event I believe the diameter of the stock cat inlet and outlet pipe is 2.5in, whereas most of the aftermarket cats are 3in. My friend used the stock cat flange as a restrictor in his midpipe to stop boost creep. So there may be some advantage of using a highflow rather than a stock cat as a starting point. Alternately, you could get a resonator which looks a lot like a cat.

 

thanks guys, the reason i asked is im doing a few things to my car this coming weekend. one was removing the air pump, and i read you NEED to have a midpipe in order to do that. I was talking to someone and they told me to just gut my hi-flow cat. Plus i dont know if the midpipe would get here fast enough.
Sorry i didnt ask my question well enough, i was at work and had little time to type. Thanks again.

 

I have never had a problem with a midpipe and I have have 2 3rd gens that I have put over 100k miles on. Go for the aftermarket. Good HP increase

 

You don't need the airpump for the cat if you're only going to run a few days without it until you get the midpipe. The airpump doesn't even come on above 3k rpm.

 

cool thanks everyone for you help!!

 

The stock cat inlet would be 2 1/2 inches **IF** it were welded better. There is a weld running around the inside of the inlet and outlet on the stock cat. This weld reduces the inlet diameter to just about 2". I had my cat welded on the outside, and ground down the inner weld to get a full 2 1/2" inlet and outlet. I noticed a slight improvement in flow after doing it

 

I have a polised mid pipe I never used. Would like to trade.