I'm going to be putting a TBE on my '05 Evo, and can't decide if I should go with a 3" free flow cat or cat delete pipe. I don't mind having to put the stock cat back on to get emissions. I'm just curious how much more HP I will get with the cat delete pipe. If it's not significant then I will just go with a free flow cat to save the hassle each year at emissions time.

 

the diff in power between a 3" hfc and 3" testpipe is 5-7whp maybe some will tell you you can gain 15whp over a hfc which i think is a lil bit exaggerated. Testpipe is real good when you want to make some serious power like adding cams,bigger turbo etc. HFC is perfectly fine for lightly modded evo,if you have emissions or dont want a loud exhaust. If you don't mind switching from stock cat to testpipe i say get the testpipe.

 

It's more like 15whp, plus quicker spool and lower EGT's. Catless is the way to go, plus is pisses Al Gore off

 

right...well dynoflash i think did a comparison with 3"hfc vs testpipe power diff was around 5whp very minimal...will try to find it if i can.

 

ams also told me around 5 whp between the two, unless you have some serious mods

 

guess he was talking about a butt dyno. Like i said unless you are planning to make some serious power 350+ the hfc is fine. when you start doing things like cams,alky,turbo etc that when you start to see the major loss in power due to a hfc, if you just plan to do a few bolt ons hfc is fine..you get good power..no annoying *** sounding exhaust, or that **** smell. Also the power diff can depend on what hfc you get some hfc flow better than others...again if you don't care switching out get the testpipe..good luck with your decision.

 

Go catless. Without question. You said you won't mind changing it out for emissions. So do it. DO IT.

 

As far as mods go, I have installed a K&N Typhoon Intake, plan to install down pipe, already have the DC Sports cat-back on order, will install Walbro fuel pump, plan to install TurboXS UTEC, and get it tuned. That's for starters. Later I do plan to install cam gears and cam.

 

yeah go with the testpipe then. What downpipe you getting...i think DC sports dp eliminates the cat.

 

Testpipe all the way.

 

I was told by Dave himself in an email that it was 12-15 difference on the dyno. I'd like to hear a sound clip of a test pipe vs/ HFC to hear the difference in loudness. I read that HFC was much quieter and that's why i went with it.

 

I looked at the DC Sports down pipe, but I want the ability to put the stock cat back on for emissions. I was thinking about getting the TurboXS downpipe.

 

I'm sorry to hear you live in a state that actually believes those power robbing beurocratic by-products (cat converters) actually help the environment.

Bottom line - to go catless you'll need a "cel fix" which may need to be unfixed prior to reinstalling cat. I would definately suggest one of those popular High folwing cats - they flow as good as test pipes and it's permanent. But costly.

 

I've seen an electronic cel fix by Perrin. I've also seen the "GP Moto Oxygen Sensor Adaptor CEL Fix" which basically puts the O2 sensor out of the exhaust flow. I'm assuming the one from Perrin is better.

 

Test PIPE