The amount of wrong info in this thread is staggering...
The maf itself is VERY VERY sensitive to changes in orientation, or even the tubing that connects to your throttle body (screens limit this phenomenon). "sealing" it is really not an issue at all.you can move it all you want, but sealing it is going to be another issue.
There is quite a bit of room to be gained in the throttle body by boring it out in the maf area... there is tons of junk cramped up there. if you have a 97/98 TB you have tons of gains going to a 99 style maf, and porting the TB accordingly.if youre doing it because you want to smooth out the throttle body, dont even bother.
Having installed many onto mostly lightly modded setups... I can say this is quite false. The m90 is deathly dependent on intake flow enhancements.Worth it? Only if your cammed and running a tiny pulley. Gains? None.
True, but by a 2% margin.... You are much better off going to another style of maf to gain head room over stock as LQ4's are nearly the same as stock when it comes to peak flow limits.Bigger= Higher ceiling.