I was looking at the Perrin unit and it seems that is has an O2 bung on the cat portion of the exhaust. (I have retained the stock mid pipe on my 2.5" tbe).

What do I do with the extra bung hole (plug it up with a bolt). Does it come with a bolt?

And there seems to be a price diff. of about $100 b/n the Helix and Perrin. Are they both a "direct replacement" cat (fit stock flanges). Thanks in advance. The search feature is beyond disfunctional.

 

I've got the Helix, it's a direct fit with no bung. Works great! No unburnt fuel smell, just plenty of power.

 

i tink helix will probably make the most power out of all high flow cats
it will throw a coad though. so you will need to get a cel fix

 

I have a 2.5" UR HFC (ceramic) right now. I do want to replace it with a metalic substrate cat. The Helix and Perrin are both metallic substrate cats but the Perrin seems to have one too many bung holes for me (where I have the stock mid pipe section with its bung hole). They are both 3" and I believe they are both direct replacement cats. Can anyone confirm this and what do I do with the extra bung hole? 1-2 whp diff. among the cats (if this is the case) in negligible so I'd rather save the $100 bucks. I'm already using the cel fix with my UR cat. I get the CEL every 1,000 or so miles. This is probably indicative of my cat being shot.

 

Interesting Thread... I would like to know which is better..

Perrin - Helix - Works HFC

 

Kind of a wierd Q but.

So Im waiting for my evo2 catback to come which is 3 inch. How does that work with the stock cat because isn't it a 2.5? Dunno if I need a different hfc or tp that is 3 inch. Then how does that bolt up to the stock dp? lol. Then if I also get a 3 inch dp how does that bolt up to the o2? Anyone know? Thanks

 

the catback necks down at the flange to fit the stock cat, and so does the downpipe. unless you get a full tbe from buschur or comparible it will neck down

 

I have the Perring HFC with about 700 miles so far no CEL. I ended up flipping the pipe 180 and using the extra bung for my wide band. This setup is great the bung sits at about 10 o'clock a couple of inches away from the dp flange when the hfc is flipped. The extra bung is for the EVO 9 rear O2 sensor. It comes with a plug bolt.

 

Is it a metallic substance cat like the Randomtech one? i want to find a nice metallic cat to change my UR hfc which is ceramic... It really kills me...

 

They are both direct replacement (fits stock flanges) metallic substrate cats. The Perrin comes with a bolt plug...

 

Anyone know of a vendor for Helix HFC's?

 

Gruppe-S, but most everyone is sold out. Check with them to find out if they expect Helix to continue production this spring.

I picked mine up from an EvoM member, that might be your best bet.

 

Yep, it looks very similar to the Random Tech unit. I'm wondering if they are made by the same company.

 

you can get both the perrin andhelix on ebay all day long