Originally Posted by Tit

I have an 05 MCS with an Alta CAI....There's a promini 15% pulley sitting on my desk at home, waiting for my MTH map to arrive....

At the moment I get about 9l/100km around town...

last week I drove 655km on 98RON (with 30km left on the range....but I didn't trust it ) on the highway....

From my dyno plot, it was evident that as soon as the SC starts adding effective boost, the AF ratio gets messy and drops very low...

The tech running the dyno pointed out that such a rich ratio was probably robbing the car of power.

In very simple terms, does the MTH tuner file usually fix this problem? So if I'm cruising at say, 3000rpm, and I'm in the 'boost band', I'm not going to be spitting un-burnt fuel out of my exhaust pipes...?

Following on from that rationale (if my thinking isn't wrong), I would guess that running MTH would give slightly improved milage on the highway...

First up, I'm going to put on the MTH with just the Alta CAI, and see what happens to the milage...then I'm going to put on the 15% pulley and see how rich the car runs for a week (more air - more fuel - lower milage?)....then put on the MTH and have another go...I'll throw up my findings when It's all done...

Originally Posted by LeeL

So, what did you get before? I have a 15% pullied S and I am lucky to get 28 on the highway. That is between 75-80 though so that might be the difference.