Is there any hard fact on the CA-spec ECU versus the rest? Im sure CA models were tuned to account for a cat and o2 sensor.

 

Yea I know you don't need all that emissions stuff, but if it's not causing any problems I'll leave it on till there is an issue. The california bikes have cats built into the exhaust, right? So unless I swap out the manifold for one w/o a cat, I don't really see the need to pull the o2 sensor and evap system. I'm not trying to squeeze any more performance out of it. Thanks for the info.

I've wondered about that too.

 

acctly
i put on Yoshimura TRS muffler on my f4i but it seems like my bike got no power on torque & horsepower compared with original exhaust.
is it because of the o2 sensor?
where the o2 sensor located ? i have no idea to find out that sensor.

 

The o2 sensor is before the muffler, but swapping out the muffler shouldn't cause any real difference in the performance of the bike. Follow your exhaust towards the engine and where you see the wires coming out is where the o2 sensor is.

 

I was tryin to find the answer to my mileage problems

I have a 2006 year with 02. I got rid of the canister put on an after market and put a resistor in O2 sensor to get rid of the Fi light.

My Mileage went from 145 to 120 per tank before reserve. This sorta sucks.

I was thinking maybe a power commander would help but I'm doubting it as the fueling is judged by the cat and O2 if I'm not mistaken.

So unless all the 2006 49 states models and all cali models are screwed with aftermarket exhaust mileage woes I'm missing something ?!

 

put your o2 back (if you cant get a bung welded in)

 

so if I put a threaded hole (bung?) in my midpipe my milage should go up again??

Isn't that part of the CAT's job? and there is no CAT on the new midpipe...

 

Yea he's saying you need to have the hole/bung put in your midpipe like it was in the OEM pipe and put the O2 sensor back in and hook it up. The cat/cats are in the exhaust manifold not the midpipe. From what I've heard on here some guys say removing the evap and o2 doesn't hurt anything and some say it can hurt your mileage. I don't see the point in doing it unless something goes wrong w/ it b/c the cat will still be in the exhaust manifold/header unless you replace them as well.

 

Thanks bro. I always thought the CAT was that huge pregnant bump in the beginning of stock pipe. ?!? Regardless, I'm gonna do this bung weld thing. Finding a nut that fit the abused threads of the O2 sensor was impossible. At the end of the it ended up being a 1/2" standard nut. Lol

Now just have to find a master welder. Muffler shops wanna rape you for this small project. Bastards!