there are 2 different lengths in the Help brand
with the shorter of the 2, u will need to the 2 in the pack
with the longer set, some have reported good luck with just the use of one

They are a long term soln.
This thread has all the info u need

 

Great job. My o2 sensor still won't fit in there so i mite need to drill it out a little more.

 

Yep works like a charm

 

gotta do this asap

 

im doin this mod tomorrow. Now i know when you do this it takes the check engine light off but i heard the code is still there for awhile. How many miles do i need to drive for the code to be totally gone. I need to get inspected soon and even though the CEL is gone im nervous the code still may be in the obdII

 

Just d/c the battery for 30 min. the hard code will be erased.

 

Remember that you have to take the car over 60mph (IIRC) to get a read. Otherwise, if you yank the neg on the battery, put it back and put right over to the inspection station, you will get a "not ready" code and fail. Then the inspection guy will think "what's he hiding", and might "look closer". Ask me how I know...

 

BTW, you can just d/c the battery, pump the brake a few times (brake light drains the battery), and connect it right back up on my VIII.

 

I have a 05 VIII and it hits the floor board. I had the reweld a o2 bung to get it to fit, but it works like a dream. No cel for 5k miles

 

Got the p0420 code this morning (cold morning in DFW, Texas) on my Evo 10 with high flow cat. I’m going to do this fix again because it worked perfectly on my previous 8 for a couple of years. Only one correction though, I believe a 1/2 inch drill bit is too large, there will be no threads left on the fouler. I think you have to use a 3/8 or maybe a 25/64 bit.

 

1/2 inch worked perfect for me, just be careful thats all

 

I swapped my Perrin catback for a cobb and now I have the same problem. I bought a CEL fix off ebay. Hopfully that'll fix it since it has a 90degree bend in it.

 

Thanks. Did you drill from the inside (where the threads are) to the outside, or from the outside (where the small hole is) to the inside?

 

Subscribed.

Going to need this when i get home next yr.

 

where could I buy that antiu fouler from? would autozone have it?
Thanks