hey guys i have a ef fairmont i can drive around all day with out it coming on but as soon as i get over 115ks it will come on any ideas

and also wat would be the best diff gears to get my car is manual and i want a bit more go it has the 3.45s already

3.45's on a manual is imho the best diff ratio. you can go higher but she will start to rev a bit on the freeway. mine does 2250 rpm at 100k's with 3.89s and auto. manual 5th gear is slightly shorter than auto, so a manual with 3.89s could be up around 2400 ish at 100 from a guess. by 110 you could be doing anywhere around 2600-2700 rpm. will be able to tell you once the manual goes in

I reckon first gear will be practically useless for take off purposes with the diff ratio i have. will most likely use 2nd for take off.

Inspect ABS pickups, they may have carboned up which can reduce the efficiency.

I've had many diff gears in my car, (WC T5) and I've found that 3.23:1 suits me best.

when I drove my brothers old EF with the 5 speed and 3.08's I concluded the same thing, Krytox. first gear was so unbelievably short, that anything over 3.45 would just about eliminate it from use.

what sorta speed can you crack in 1st gear with the 3.23's? and what RPM does it drop to between full throttle changes on acceleration from standstill?