Topic: High flow cat opinions

[stan98tj]

Im looking to replace my existing stock cat. The thing is pretty much shot. Id like a high flow cat to match the high flow exhaust i have (banks header/cat-back). Im not too sure about the available brands. Im considering Random tech's High Performance for $280. Ive read a few reviews that said they are pretty good.
Any opinions on good high flow cats?
will this make the exhaust any louder or help cut the noise? Dont want it any louder haha.

[chitchc2]

This may help out:

http://www.installuniversity.com/install_university/installu_articles/cat_flow_test/cat_results_discussion11.122001.htm

If I'm reading this correctly the author is stating that optimal performance is obtained at 2.2 cfm overall exhaust flow per hp (now he doesn't clarify where to measure that hp but I suspect he means crank hp and not brake)
If you assume that the average standard CAT flows at 280 CFM then it would be "optimal" for a 127 crank hp engine.

What does all that mean? It means that you would only benefit from a higher flow CAT if:

1) You have enough modifications on your AMC 150 to get it over 127 chp
2) The rest of your exhaust system isn't creating a flow restriction greater than the CAT

My guess is that any after market CAT that is "High-Flow" is suitable for our 4 bangers unless you have major engine modifications

One more note: I'm not an expert on this at all, this is just what I found while researching what to do with my TJ.

[stan98tj]

This may help out:

http://www.installuniversity.com/install_university/installu_articles/cat_flow_test/cat_results_discussion11.122001.htm

If I'm reading this correctly the author is stating that optimal performance is obtained at 2.2 cfm overall exhaust flow per hp (now he doesn't clarify where to measure that hp but I suspect he means crank hp and not brake)
If you assume that the average standard CAT flows at 280 CFM then it would be "optimal" for a 127 crank hp engine.

What does all that mean? It means that you would only benefit from a higher flow CAT if:

1) You have enough modifications on your AMC 150 to get it over 127 chp
2) The rest of your exhaust system isn't creating a flow restriction greater than the CAT

My guess is that any after market CAT that is "High-Flow" is suitable for our 4 bangers unless you have major engine modifications.

interesting point. now the other issue is quality. i want something that has a good reputation and will last.

[Jeffy]

Forget Random Tech.  Look at Magnaflow/Carsound.  The bolt on cat is $150 less.  You could go cheaper with a universal but I like the bolt-on's.  Several members are running the Magnaflow.

[stan98tj]

Forget Random Tech.  Look at Magnaflow/Carsound.  The bolt on cat is $150 less.  You could go cheaper with a universal but I like the bolt-on's.  Several members are running the Magnaflow.

Jeffy i think i remember you saying that a hi-flow cat would quiet down the exhaust. is the magnaflow a high-flow?

[Jeffy]

Jeffy i think i remember you saying that a hi-flow cat would quiet down the exhaust. is the magnaflow a high-flow?

A Cat will quiet the exhaust.  Run it as a straight pipe then put the cat on and you'll quickly realize how much nicer it is with the cat on.  Yes, the magnaflow is a hi-flow.  Do a search on 'carsound'.

[stan98tj]

A Cat will quiet the exhaust.  Run it as a straight pipe then put the cat on and you'll quickly realize how much nicer it is with the cat on.  Yes, the magnaflow is a hi-flow.  Do a search on 'carsound'.

thanks Jeffy. Magnaflow it is.

[stan98tj]

magnaflow doesnt make a hi-flow cat for a 98 2.5l. they make them for 00 and up.

[Jeffy]

magnaflow doesnt make a hi-flow cat for a 98 2.5l. they make them for 00 and up.

It's not that they don't make one.  It's just that it's a universal.  (99005HM)  This is because the stupid cat is welded on with no joints.  They aren't able to be replaced as easily.  You can see for the 4.0L, that they had to replace the whole down pipe as well. Jeep changed this in 2000.

[jfrabat]

Forget Random Tech.  Look at Magnaflow/Carsound.  The bolt on cat is $150 less.  You could go cheaper with a universal but I like the bolt-on's.  Several members are running the Magnaflow.

I'm one of those; no problem with mine so far except I had to welded up to the exhaust pipe because it came loose on me once (and I am not a big fan of EXTREMELY noisy Jeeps!)

[stan98tj]

(and I am not a big fan of EXTREMELY noisy Jeeps!)

same here.

[chrisfranklin]

Somebody's cat doing a stand-up "high-flow"  Had opinions before he got "fixed."

The Car sound/Magnaflow I got last year based on recommendations here seems like it worked out pretty well.  I got mine at O'Reillys, and in California, for only around $200.