Catalytic Converters - what size??

Submitted: Wednesday, Jun 22, 2005 at 12:28
ThreadID: 24080 Views:1356 Replies:4 FollowUps:4
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The exhaust on my 3.3ltr V6 Pathy has had it and I’m in the process of arranging to have it replaced with a 2 ¼ system. The old system has 2 inch pipes and 2 x 2 inch catalytic converters.

I have been told to upgrade the catalytic converters at the same time as the pipes/muffler. One place has suggested 2 x 2 ¼ inch normal cats, another has suggested 2 x 2/14 inch high flow cats and yet another has suggested 1 x 2/4 inch high flow cat (2 pipes in / 1 out).

Now I am confused as to which way to go. Obviously it would be nice to pick up a few extra hp. I would have thought that 2 x standard 2 ¼ inch cats would be an improvement over the current set-up???

Does any one have any experience or suggestions on which way I should go???
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Reply By: Moggs - Wednesday, Jun 22, 2005 at 12:29

Wednesday, Jun 22, 2005 at 12:29
sorry...typos...all cats were 2 and 1/4 inch in size
AnswerID: 116876

Reply By: flappa - Wednesday, Jun 22, 2005 at 12:49

Wednesday, Jun 22, 2005 at 12:49
Get hi flow Moggs. Cats and Mufflers. Can make a HUGE difference.

Hi flow muffler made a big difference to my PJ.

When you look at a hi flow , compared to a normal one (either cat or muffler), when they are pulled apart , you will quickly see why they are better.

From memory (was about 18 months ago), the standard muffler went from 2 , 1/4 down to 2 inch through the muffler , then out again to 2, 1/4.

Its now 2, 1/4 ALL the way through.
AnswerID: 116878

Follow Up By: Moggs - Wednesday, Jun 22, 2005 at 13:46

Wednesday, Jun 22, 2005 at 13:46
Hi Flappa, yep, the more I read on the net and around the forums the more I am swayed towards getting 2 x 2 1/4 inch high flow cats. Thanks for the info.
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FollowupID: 372364

Reply By: Member - Crazie (VIC) - Wednesday, Jun 22, 2005 at 12:57

Wednesday, Jun 22, 2005 at 12:57
Come on Moggs, 2.5 inch all the way through, 2.5inch hi flow cat, get it sounding like the jack, i know you want to hahaha. Call Geoff at Trufit moorabbin, 95555688.

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AnswerID: 116879

Follow Up By: Moggs - Wednesday, Jun 22, 2005 at 13:49

Wednesday, Jun 22, 2005 at 13:49
LOL, nah, could never compete with the Jack...anyways...I want my kids to sleep on those long drives - aint going to happen if it sounds as sweet as the Jack.

Thanks for Geoff's number. I have just called him and his price was the best by far for the system - looks like it will be going in on Saturday :)

BTW, all the best for the big trip on Friday - hope it is great and the tracks dry out for you - am bloody jealous BTW :-)
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Reply By: Exploder - Wednesday, Jun 22, 2005 at 18:55

Wednesday, Jun 22, 2005 at 18:55
G'day Moggs>Just a Quick point.

Does the pathy engine require some backpressure in the system?
If so a full flow exhaust is not a good idea, as you can lose power or move the power band, generally into the higher rev range.

Sorry it probably all seemed so simple till I brought that up. Probably the best thing to do is to talk with you club (If not already done) and see what sort of set up’s others are running.

I think you should be right but not many engines around, that don’t perform better with a hi-flow exhaust.
AnswerID: 116938

Follow Up By: Moggs - Thursday, Jun 23, 2005 at 00:20

Thursday, Jun 23, 2005 at 00:20
Hmmm....hadn't considered it would be a problem. Should be ok though - a caouple of Pathy owners who frequent the club forum have had the same system installed and reckon power has improved - especially gear holding when towing uphill. I also found that most of the exhaust shops I spoke to had done it to Pathy's before with happy customers .... (or so they said)
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FollowupID: 372478

Follow Up By: flappa - Thursday, Jun 23, 2005 at 10:04

Thursday, Jun 23, 2005 at 10:04
If you stick with the same size exhaust , but just Hi flow , it should be a problem.

Its when you go bigger in actual size problems occur.

When I did mine , they said no bigger then 2 1/2 otherwise problems could occur.
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