Opening stock cat to 3" in & out????

[Kurt 97 GTS]

Opening stock cat to 3\" in & out????

I currently have a Borla cat back and am adding Belanger headers. I thought that I would also add high flow cats at the same time and be done. Several people have informed me that they would just open the stock cat to 3" in/out and skip the high flow cats.

Do you think this set-up would be too loud with high flow cats? If I kept the stock cats and opened them to 3", how much would this really help - any additional HP, would it run cooler, etc.??

Thanks in advance for your advice and comments.

 

[Vipermed 97.01]

Re: Opening stock cat to 3\" in & out????

either remove them and put some good bullits in their place or put high flo,changing the inlet and outlet size is not changing the density of the very restrictive oem cats

 

[Casey]

Re: Opening stock cat to 3\" in & out????

Kurt, I have the same setup. Belanger, borla 3". I went with Roe 3" high flow cats and made it 3" all the way through!
Sounds great! Much cooler, should of added some HP as well! Can't say how much as I put the whole system on at the same time.
Not sure about the OEM cats, but what Vipermed said make sense, stock cats would still be more restrictive!
Good luck, you will be very pleased with you new additions!

 

[HP]

Re: Opening stock cat to 3\" in & out????

Click onto the JC Whitney online catalogue and pick up 3' of stainless
steel pipe - get the thicker offering. Cut in half - you will have enough
to replace the cats on both sides - with a few inches left over.
Cut the reduced section off the side resonators - and weld the section of
SS pipe to that - if you don't weld - just take the sections to a muffler
shop - that way they won't give you a hard time.