True story lol. I was booting it at about 4k rpm in second and I put the clutch in and BANG, the guts of my cat got blown out the back and I could see them bouncing all over the road (thanks to my 4499s). I then took my cat off to gut it, but it seemed it was already fully gutted from that. It now shoots flames out the back on deceleration and heavy gear changes. Looks awesome lol. Only does it because the car is running incredibly rich though.

All I know about Cats is "CPSI" (Cells Per Square Inch) the rest of the sales pitch for these things usually means nothing more than a reason to over charge you.
The more CPSI the more restrictive the Cat is going to be.
You can get Metal cores & you can get ceramic cores.
The metal core cats are normally more robust & usually give a better flow.
A factory cat will usually have a higher CPSI (about 400 CPSI) to be emissions legal & these usually have a ceramic guts/core.

An after market High flow job (usually 100/200 CPSI) will have more flow & give better performance but may not pass the emissions standard, especially if you have headers/extractors or a mildly worked motor.
If you are running a Turbo or Supercharger with an after market sports exhaust system with a high flow cat, then good luck if you ever get nabbed by an irate transport gestapo inspector or you have to front up for an over the pits machinery inspection.

Stock falcon cat is 400 cpi and a High Flow cat is 200 cpi or the new type 100cpi. I noticed a small gain in midrange power when fitting a magnaflow 200cpi cat. At full throttle it revs out better aswell.............only a small difference but it is noticeable. The biggest difference you will notice is that your exhaust note will sound heaps better:)

im replacing my cat and for an extra $20.00 i can get a highfow unit which i think ill go for if its gona get my better ecomony and performance, as my current cat seems to be empty and rattles abit as certain RPM's.

http://www.bestmufflers.com/bshop/produ ... 7f45a2407d

http://www.bestmufflers.com/bshop/produ ... 7f45a2407d

http://www.bestmufflers.com/bshop/produ ... 7f45a2407d

I had a guy come into work today with a turbo wrx, said he got EPA'd for noise & ended up having to do a full emissions test, his 200cpi high flow cat didn't pass emissions, so a 2nd has been added, not sure how it was fit tho, and the car passed the emissions test. Was interesting to hear that.

I currently have a 2.5" a/c delco cat which i think is 400cpi. It flows better than the stock falcon item, still emissions compliant but could flow better lol.

Cheers

ToranaGuy

With my old motor fitted with a 1673 cam, itd spit a flame at changes up or down at about 5k rpm, or popping off the limiter skidding. This was with a chip and tune, was running fairly well. Hopefully the new motor and cam will do the same thing haha

a hi flow cat will make a difference, but not noticable. standard i think they flow 175cfm. i just put an xforce in mine, flows 250cfm. mine was already 2.5" exhaust bein an xr6 thou.......i did hi-tek headers, xforce cat and mufflers and full stainless 2.5" system....not loud at all and wenr heaps better