I find it much easier to go from the bottom, i don't even bother taking off the wheel. Takes about 15 mins.

I have the greddy elbow with the extra injector bosses on it, so it makes coming for the top almost impossible unless you take it off, which is much more of a pain than just jacking the car up and going from underneath.

would it be fine to go with all #9's my only mods are PFS catback and airbox mod

IMO, no. Stay with the stock 7's and 9's.

Running the wrong heat range will cause worse gas mileage and fouled plugs.

Cheers :)

easy way to remember...the front coil goes to the front rotor -top (trailing), and likewise for the rear. Middle coil...the one with two leads...it hits the bottoms (leading)