Ah. Mine stock has a dual 2"in and a single 2.5" out w/ O2 bung in cat. I was going to convert to a 94039 (3" SI/SO ceramic w/ single O2 bung) but now I'm thinking a 99039HM (3" SI/SO heavy metal w/ single O2 bung) due to the comments about Ethanol that JasonW made. Hoping there aren't to many downsides to this setup. I'm trying to tell myself the 3" I/O may give me a little more revs than what I have on there now which would be much appreciated during hauling the camper plus trailer full of dirt bikes over the pass while trying to hold a steady 75MPH.

 

Up here, most places only put 10% ethanol into the 89 octane fuel. The 87 and 91/92 usually don't have it, with the exception of Shell stations (they put ethanol in everything except 87). There is no 93+ up here.

 

Hmm. Maybe I just need to pay better attention. Maybe I could get the good gas all along...well considering it's still oxygenated in the winter, no lead, etc. etc.

 

I threw a check engine with both the 94xxx and 99xxx, but I am an exception. For some reason I am killing cats (humanely of course ) but I don't have the money to throw at it to fix the problem yet. I'm shooting for this summer but in the mean time to keep the cel off, the non-fouler trick works for me.

 

Nick if you have to hear what one will sound like shoot me a pm with yr cell number and I'll go kick mine over.

 

im running the 990069HD, 3in SI/SO, with two bungs, on for sensor and the other for A/F. Mine works great and has never thrown any codes, that being said when my plenum blew again it messed my cat up so im installing another one (same kind, just got it yesterday ).

If your running no cats and it just going straight to a muffler it will be a little muffled with the cat on, compared. But it will still sound amazing and deep.