Hahn MODpipe and 3" cat back :)

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Mar 5, 2009 | 12:33 AM

#51

HunterKiller89

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From: Los Angeles

Quote:

Originally Posted by TCASON

This is as close as anyone has posted so far for a comparison, and I do not think anyone will go that far.

There's no logical reason why someone would upgrade their DP for the same stock diameter just to have a high flow cat.
3" is going to be the best option for the stock turbo ( dyno proven that it does allow higher Hp & Tq output ) & it's already there for those that upgrade their turbo's down the road.

oh, no. i completely understand. Its just that the two in this thread are arguing how restrictive OEM style cats are opposed to after market ones. I just explained how to show the differences...but seeing as how, like you said, no one will buy a stock sized DP as an upgrade, theres no point in making one or testing one.
I was just trying to avoid one of them saying "see how restrictive stock cats are?" when the cat isnt the only factor that changed in your testing.

Mar 5, 2009 | 12:35 AM

#52

steddy2112

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From: Newark DE

Quote:

Originally Posted by 1badBlueberrySC

Look inside of it... you will be able to tell.... thats how I know... GM put 2 in there I am sure to pass Emissions testing, they wouldn't sacrifice any "FLOW" or let alone put in 2 cats if they were high flow!

One is a start up cat and one is a main cat.

The start up cat flows damn well and so does the second cat.

We wouldn't soot if the cats sucked

Mar 5, 2009 | 02:17 AM

#53

1badBlueberrySC

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From: Raleigh, NC

Quote:

Originally Posted by steddy2112

One is a start up cat and one is a main cat.

The start up cat flows damn well and so does the second cat.

We wouldn't soot if the cats sucked

Steddy... I'm gonna smack you! OE cats don't flow good, EVER!

Mar 6, 2009 | 02:43 PM

#54

Terminator2

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Joined: 07-25-08

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From: Florida

Quote:

Originally Posted by TrevMo

Not trying to be a jerk....but how do you know? I don't have any factual info to back up my assumption...just wondering if anyone has some data out there that can support the need to replace the cat...

Clearimage auto tested the stock DP to flow 299 CFM. High flow catted DP flows 400 CFM as tested. Stock hotside charge pipe flows 300 CFM as well and their replacement chargepiping flows 480 CFM. One other interesting point, the stock catback is actually 3" from the flange to a couple inches before the resonator. It then necks down to 2.5"

Quote:

Originally Posted by steddy2112

One is a start up cat and one is a main cat.

The start up cat flows damn well and so does the second cat.

We wouldn't soot if the cats sucked

The factory cats appear to be high flow but the flow data shows otherwise. A 3" high flow cat should be 400 CFM+ not less than 300 CFM. These cars consistanly gain 10-15 whp with an aftermarket DP catless or not.

Quote:

Originally Posted by HunterKiller89

that doesnt aid much in the argument of how good a stock cat converter will flow. the stock DP is 2.75inches and tapers down to 2.5 at the bungs. Of course a 3" will flow more. Its good to see you're testing your stuff though

a true test would be to take an OEM cat, and an aftermarket cat of the same in/out diameter, and flow test those

It is 3.0 inches except at the bung where it is crushed to approx 2.5 inches.

Quote:

Originally Posted by TCASON

This is from the thread,
Flow Bench results:

"Stock down-pipe = 299 cfm (Weighs 17 lbs.)
Clear Image 3" down-pipe with hi-flow cat converter = 400 cfm (Our down-pipe was good for 15 HP to the wheels): (Weighs 10 lbs.)"

I just noticed your post. You beat me to it.

Last edited by Terminator2; Mar 6, 2009 at 02:44 PM. Reason: Automerged Doublepost