Two cats, 1 on each headers is always better than having twice the air flow trying to go through a single cat further down the ypipe.
check this out .... http://www.installuniversity.com/in...on11.122001.htm

Each pair of catalytic converters restrict about eight ( rear wheel horsepower on stock LS1’s. David Vizard’s research shows that 2.2 cfm of flow at 20.4” of H2O will support 1 horsepower. 2.2 cfm is the optimum flow through the exhaust system and reflects open pipe flow. Assuming that the average LS1 puts 300 horse power to the ground, that is a 2.67% increase in power.


So for a stock LS1 that puts 300 to the ground and still has both cats but on a 2.5 inch y pipe.. An 8 rwhp increase happens when the cats are removed...

HP= Flow (cfm)/2.2 cfm 567.8 cfm/2.2 = 258.1 horses..
This means that the stock cats can support up to 258.1 horses...
("looks" like study was done in 1999)
So if i want two carsound cats they will flow 372.7 each x2= 755.4cfms

745.4/2.2 = 372.7 hp 2.5 inlet/outlet carsound cats can support..
I wonder if 28 inch H20 flow tests were for 3inch cats.. im not sure..
If thats the case then 2 3inch carsound cats can support 436 rwhp without losing any power at all...

Sounds good too me...
I'll be picking up some ebay carsound cats.. and having a custom built manderal bend y pipe...

 

3" Carsound on the end of my hooker Y-pipe. Works fine for me

 

Thanks

 

hey...i jsut got Hooker LT's and i need to get to carsound cats for 32.95 each, BUT WHERE???? please tell us..im doing the exact same thing as you...cause i have to take out my airpump and all that BS stuff, so might as well add another cat so i can pass the SMOG test...
randy
if you will email me at randysatterfield@hotmail.com

 

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2447503298

OR, just search Ebay for CarSound....I just got like 35 listings. You'll find that there are several different places that sell them.

 

did you get the 3 or the 2.5?
i think i will go with the 3..
randy

 

also the 94100 or the 94000?
i think the 94100 since its smaller....

 

2.5
I went with the 91006. It's a tiny one that most don't stock. The ones that didn't stock it wanted like $100 for each. Performance Curve, one of the listed sellers on Ebay, stocks the 91006 model and the bill was $80 to my door for both. These sites will help you understand the variations between the models...if you didn't check it out already.
http://www.magnaflow.com/
http://www.promuffler.com/catalyti.htm
http://www.exhaustproslinc.com/uncon.html

BTW, MagnaFlow and Carsound are the same exact part, only the MagnaFlows are polished.
Hope that helps.

 

why not the 3? cause i have a full 3inch catback!!
what size are the hooker headers?

 

After talking to several different people/places it was decided that a 3' y-pipe into a 3" cat back was overkill. The 2.5 is plenty for what I have. Plus, the tiny 2.5 version helps w/ space.

 

also what is the differnce between NO AIR and AIR...
randy

 

so get the 94106 the 2.5?

 

I assume if you got rid of the air pump then you don't need one w/ an air tube. The 94106 should be fine, just find someone on Ebay that stocks it.