If I am not mistaken, and feel free to prove me wrong, but fuel trims only effect closed loop, or cruising fuel trims, not open loop, or wide open fuel trims. If the car feels slower under full throttle, relearning fuel trims won't help anything.
Dan

 

I haven't heard closed or open loop in years so I really don't remember **** about it lol, so I can't confirm or deny that.

 

thats correct. once WOT and open loop the trims are pretty much ignored.. doesn't mean you can throw injectors in a car and not set latencies or scaling though.

the transformation from closed to open will slightly effect the wot pull from the beginning though. (Closed Loop) LT Trim Control.

to really effect a tune you have to change the injector scaling or latency, then you will throw off the trims permanently until you rescale and the fuel map will be inaccurate depending how much scaling was changed as well.

on evo X's if you dont mod that trim control you can really damage the motor... not so much on evo 8/9

 

I'm with you 100% on setting injector sizing and latencies. That is the first step to a good tune.
Dan