i was always wondering where those numbers coming from. Did you put it on the dyno,when you swapped them?

 

If the cat is more restrictive when hot, then everyone in Redline street class should move their cat to the tailpipe location where it will run cooler.

 

Stay with the testpipe, you will definitely feel a decrease in performance with the HFC. If you want to kill some of the drone weld a small resonator or muffler into the testpipe. My friend put a Buschur bullet muffler into his testpipe and it really mellowed things out (3" BR turboback with bullet muffler). His system with the 2 bullets is almost as quiet as my BR turboback with the Magnaflow muffer.

 

I switched from an HFC to a test pipe, and even without a tune, it helped out very significantly. Also much louder. My dad took my car to run to the parts store this evening and I could hear my car a mile away, literally, a MILE away. Almost obnoxious, but I love it. IN the car it's not that loud.

 

+1, this is what I did.

 

An avarage cat working around 1800 farenheit. Below that, will not working properly. That is why every manufacturer try to place them as close as can be, to the engine.The cold cat does next to nothing . If you will have the HFC and place it all away back, it still will be more restrictive but less vs the closer placed to the engine. Theoraticly. But i dont know it will actually worth to do it. In the RTA. they looks like will use a sniffer to check the car. I think you need to pass.
Besides if you have enough power, you shoot flames when everything is hot . So the heat will move all the way anyway.
From:

SAE Publications Group.
Gas Direct injection Aftertreatment and
Exhaust Aftertreatment Modeling:

"SULEV and "Off-Cycle" Emissions Benefits of
a Vacuum-Insulated Catalytic Converter"

"Ex. gas temperature (°C) 950 - 100 -800
Ex. gas flow rate (g/s) 20 - 130 - 40
Vibration load (g's) 28 - 60 - 30
Vibration frequency (Hz) 50 - 2500 - 100"

"Table 4. Reduction in FTP Emissions of VICC vs
Conventional Converter
Soak Tci HC CO NOx
(h) (°C) (g/mi) (g/mi) (g/mi)
Extended Prep Cycle to Fully Melt PCM
12 315 -72% -75% -70%
18 285 -65% -66% -63%
24 204 -28% -25% -25%
36 106 -9% -7% -9%
Standard (1 UDDS) Prep Cycle
12 212 -30% -27% -27%
18 152 -17% -13% -16%
24 110 -10% -7% -9%
36 61 +4% +6% +5%"

 

 

The best solution for those not wanting to run a test pipe is a 100 cell race cat. Here are some recent test results vs. ceramic HFC's.

Here are some recent dyno results from NorCal showing the superiority of the 100 cell cats:


+22whp/+19tq on a Mustang Dyno. Ultimate HFC & MBC vs. 100 cell race cat & ECUboost.

http://www.norcalevo.net/index.php?o...2280#msg422280

+21whp/+11tq on a Mustang Dyno. VI$H you-know-who HFC vs. 100 cell race cat and Sun Hyper Force.

http://www.norcalevo.net/index.php?o...4330#msg424330