mr220v has it right...
and don't forget a VERY important detail....
Putting a larger maf on and engine it wasn't designed too and you will run into this problem (well its easily fixed but yea)
Larger maf = less flow through needed (velocity) = incorrect voltage reading = ECU believes you are at a lower then actually load and advances timing....
I don't need to fill in the rest :P
I have a smt6 in my Tacoma with a 2jz supra maf and i logged the OBDII system which PROVED right away that the ecu doesn't know where in the load range it really is and i noticed and increase between 3-5deg of timing over stock maf. Of course the truck hauls ass and the 5vz can take the added timing but i used the smt6 to pull back some timing up higher and in the low rpm high load ranges to keep things safe. Also had to do some fuel adjustments to.
Soo don't forget about timing
