Keep the stock airbox and throw in a K&N Filter. There is no need to change to an aftermarket intake since it doesn't do much for gains. You can eliminate the sound generator as it's a simple DIY mod from Home Depot/Lowes. The thread link is below.
https://www.ft86club.com/forums/showthread.php?t=72263
Catback can depend on everyone for sound, unless you're relying on weight reduction, then a single-exit would be beneficial compared to a dual exhaust.
E85, OFT (Open Flash Tablet), UEL, Catback is enough to gain a good amount of power while eliminating the torque dip. If you have the extra $$$ to spend, then I would advise going with the EcuTek over the OFT.