I'd go with what Dennis told you...
the theory behind the GT Mustang MAF is that it's designed for
a lower volume of air (NA) and that by using a lager percentage
of the transfer functions (table) in the GT Mustang MAF your
metering is theoretically more accurate than using a smaller
percentage of the LMAF's (larger) transfer functions (table).
I suppose this is all true, but if Dennis didn't feel it was
necessary to make the switch, then I wouldn't worry about it.
I'm ASSUMING he's getting that info from "you know who" -
if that's the case, I'd feel very comfortable using the (L) MAF
you have.
As far as filter setups - THAT is a controversy that will never
go away. Simply put - I haven't found K&N filters to be a problem
with respect to MAF wire oiling (so far). They shouldn't be
cleaned very often, unless they practically have a solid coating
of mud on them - I posted a long writeup in the old Forums on
proper oiling techniques a few months ago. If you want to read it,
I'll find it for you.
Cone or panel filter? I've gone back to using a K&N panel filter,
from using an Autophysics cone, and my stock air box of course,
simply because it's simple and easy to maintain and I've got a
totally sealed system that keeps heated under hood air from
elevating my intake charge. No one, so far, has proven a cone of
the same surface area provides any additional power. I suppose they
do provide a certain level of satisfaction with respect to the
wood factor however and that's the main reason, I'm guessing , you
see so many of them being used. If you want to use the oem style
paper filter instead - go for it, just change 'em pretty often.
Good luck with the mods, I hope this helps,