cthcky5

iTrader: (15)

i no the diffence between the two. right now i am running a hfc and i am thinking about switching to a test pipe. what are the pros and cons between the two?
thank you
Dan

JakeTheVIII

iTrader: (35)

One is illegal. That's it.

MR Turco

iTrader: (16)

they are both illegal.

Ebirns99

I just switched from a hfc to a test pipe. I love the sound that the car makes now much more throaty. There was a little power gains. One thing that may be a con unless you enjoy is how rich the car smells when its on. But all in all im happy with my move to the test pipe.

JakeTheVIII

iTrader: (35)

Oh, really? I always thought the advantage of a HFC was to keep it legal (emissions). Why would you pay more for a HFC than a test pipe? So it looks like a cat? Good thing I don't have to do emissions in my county, I run open exhaust all the time.

bluebanana23

iTrader: (26)

If you change it will smell worse, be louder, if noticed by a cop-big fines depending on state. High flow cat is illegal as well if it can't pass emissions and/or you changed it from a cat in good working order.

P_ham

Search! There has been countless threads on this.
https://www.evolutionm.net/forums/sh....php?t=173005&
https://www.evolutionm.net/forums/sh....php?t=182743&
https://www.evolutionm.net/forums/sh....php?t=203712&
https://www.evolutionm.net/forums/sh....php?t=272135&
There were many more

MR Turco

iTrader: (16)

Altering any emissions equipment is subject to large, federal fines if you are caught not saying you ever will.

The advantage of the HFC is you dont smell like fuel all the time.

srcevo8

iTrader: (10)

The two big things to me are (1) smell and (2) some HFC's can pass a visual test. Most TP's don't look remotely like a stock cat so if a cop takes a peak you're screwed on the spot.

TP would provide better gains though.

Davethewave

iTrader: (9)

im debating whether or not i should have my welder put a shroud on my test pipe to make it look like a cat...

i dont think a cop is going to get down under my car in the even i get pulled over, virginia cops have that "high and mighty" prowess. i think he that he would think that would be beneath him.

when i switched from hfc to tp, the throttle response was improved greatly, i dont think i'll ever go back.

cthcky5

iTrader: (15)

thanks for the help.. when it comes to emissions would u use the stock cat or the HFC?

what are the hp gain differents?

thanks
Dan

vaboostn33

For emissions just swtich to the stock cat to be on the safe side, then after you pass, just switch them back. Iv run a test pipe on both of my Evos from the day I put an exhaust on them. Yes, SOMETIMES you can get in more trouble from the law with the test pipe. But you pay to play. Most people know what they are getting into when they buy an Evo and start modding it. Personally, I love the added sound/smell from the test pipe. And yes, there is a good amount of performance gains from it too.

cthcky5

iTrader: (15)

excellent, thanks everyone

Ebirns99

What is the fine exactly..i know it changes from state to state but has anyone been caught? and if so what did you have to do

deuce329

iTrader: (2)

I switched from a hfc to a test pipe, turbo spools quicker and gained roughly 15tq and 10hp on dyno that was after a new tune with the test pipe. Exhaust is definitely louder at all RPM's.