Hey,
Just got my 2 high-flow CATs today (got them on eBay for $60 a piece) the box says high-flow, they look like CATs, but they look similar to the stock cats on my 97 F-150 v6. Is the "high-flow" part have something to do with the way its designed inside? if I just paid $120 for the same thing I already had, I will be mad. Also, by going to high-flow cats, do I need my pre-cats?
-M

 

the 2 hi flo's will replace your 4 factory cats. You should use 2.5" diameter inlet/outlet.

 

Hi, the high-flows are only 13" long and are 2.25" diameter, as is my muffler and exhaust tips. My trucks only 7 years old and has 79k on it. Will an exhaust shop replace them for me? EPA regulations seem tough.
Thanks
-M

 

Im guessing you have the 4.6 V-8.
2.5" inlet/outlet is reccomened for these engines.
yes they should replace them since the hi flos are completely legal. 2.25" pipe should work for the pipe size, but im not sure if it will work with the inlet size from the manifolds.

What kind of mufflers did you order?

 

I have the 4.2L V6 actually. I was told in a different post that stock size on a 1997 4.2L V6 was 2.25. I ordered a Ravin Z-33 muffler