i have a 99 ford expedition with the 4 6 in it i have a k&n cai a poweraid tbs hypertech programmer and a magnaflow si/do exhaust will i notice a difference in power with high flow cats and a less restrictive y-pipe as well and if i add a jet maf sensor will it get rid of my lean code or is there a way to get rid of that with out custom tunes.

i appriciate all the help i can get thank you

 

Just a minor increase, barely.

 

YOu are destroying your engine running lean with a tune that can't handle the CAI. Take it off until you can get custom tunes that will mix the proper fuel with the air.

 

what would happen if i continued to run the lean code would replacing the maf sensor and fuel filter get rid of it or not help at all

 

You are masking the problem. The computer can't handle the air/fuel mixture. You will burn up the engine, running lean

 

you wont gain anything on that engine with a new maf, lose that stinking tb spacer