Welding on high flow cats...

[Toby]

I am thinking about getting some high flow cats (on my 2001 ACR) while I am putting on my new Borla system and wondered about any hints on the install.

I assume you just take off the stock cat and the pipe it's welded too...cut it off...weld on the new one and then attach the rest of the exhaust behind it.

I assume the new cat length will be the same as the stock?

now I assume I should get the standard random cats from parts rack..2 1/2 inch size pipe on the cat. right? I don't plan on doing any mods to the engine and could care less about a few HP difference.

Parts rack shows a pic of a 3 inch on a 2 1/2 inch pipe and it looked liked overkill...it had reducers on both sides. If one needs a 3 inch cat...why not just go with a complete 3 inch exhaust and do the job right?

 

[SapphireGTS]

That pic that Jon shows is of my car when my buddys shop did the install. That is how he sends them so its not 100% viper specific. You do have to do some welding. The reducers ar on there because I still had the stock flex pipe. I now have a full 3 inch exhaqust and have since ditched the flexpipe. Good luick.

 

[ViperJoe]

I have RT hi-flows with the 3" Corsa. I welded the 2-1/5 to 3" adapter to the cat and welded the 2-1/5 up to the curved header pipe. I marked everthing circumferentially and added a couple of horizontal line-up orientation marks, pulled off the curved header pipe and welded everything off the car. Everything went back perfect.

 

[Mighty GTS]

Viper Joe,
I am doing the same thing to my car. I order the
RT ceramics from JonB. He is sending a 3" extension
to weld onto the Corsa. HE said you cut off the few inches of the 2.5" corsa until it is 3" right at the
muffler, essentially giving you 3" out of the corsa to
the 3" cat, then reduce the otherside of the 3" cat
to mate to the 2.5 inch header pipe. Does this make sense?
JOe.

 

[Mighty GTS]

Viper Joe,
I am doing the same thing to my car. I order the
RT ceramics from JonB. He is sending a 3" extension
to weld onto the Corsa. HE said you cut off the few inches of the 2.5" corsa until it is 3" right at the
muffler, essentially giving you 3" out of the corsa to
the 3" cat, then reduce the otherside of the 3" cat
to mate to the 2.5 inch header pipe. Does this make sense?
JOe.

 

[ViperJoe]

So you have the old 2-2/2 inch Corsa systems?
And you are going to delete the 2-1/2" pipe from the rear of the cat to the rear Corsa mufflers?
Sounds like a winner but where are you getting that 2" pipe from?

Also I had to take an inch or two off the rear of my cat exit pipe so that the front cat pipe wasn't shoved up so far onto the curved header pipe. It was almost all the way up at the bend. When I shortened the cat it fit more onto the straight part of the front curved header pipe.
Good luck, you'll love the sound!

 

[sbkim]

Toby - I apologize if you answered this before, but did you end up welding the cats on or did you use the band clamps

 

[Jerry Dobson]

No "unbolting" the factory cats. You have to cut them off of your header flex pipe.

 

[sbkim]

yes - what I meant was after you cut the factory cats off, then can you band clamp the new high flows?

 

[Mike Adams]

It is not necessary to weld the cats on. I usually use a sawzall (don't know how to spell it)and cut off the cat at the front weld. Then take the reducer from Random Tech and cut 2 slits in it so it will crimp better, and just use a standard 2 1/4 muffler clamp to clamp the reducer to the front turn around pipe. If you buy a Corsa or B&B they already come with 3" inlets and you just cut the random tech to fit the distance form the cat back to the front pipe. On a Borla you will probablely have to cut the Borla where it reduces and expand it at an exhaust shop just a little to fit the 3" ramdom techs.

I usually don't weld stuff if possible that way if you wish to put on headers later it is not such a big deal.


Here is a picture of a Corsa I did last week with Random tech metal substrate cats onto the stock front flex pipe. Note this is before tightening up clams

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