I would definitely bote going the performance route, and although I would usually never do so, I would recommend a Nismo performance part, as you already have the stripes which currently represent....nothing.
The HP downpipe would likely not do much for a car with a stock I/H/E...it is a great component part in an exhaust system, but on a stock car alone, I don't think you would release it's potential.
I wouls always recommend against neons. They will piss you off somehow, wether it's by the cops fcuking with you, one of them breaking, or people flaming you(because you'd deserve it) p.s. neons scresm "STEAL ME" or "I'VE GOT A SWEET STEREO...JUST BREAK IN AND FIND OUT!"
Nismo rims are not worth the money, plain and simple, there's no way around it. You wouldn't buy a Nismo Spec V that was an exact replica of a regular Spec V, with no mods other than the badges, for an extra $4,000 on the sticker. (or would you, some of the suckers are now asking lmao)
A Nismo spoiler would be expensive overall, with installation and such....and definitely not be worth it. It woes pretty much nothing.
A Nismo rear lip kit would not look right ever, IMHO, but definitely not a chance with no full body kit, if that's your bag.
LMFAO @ Apex APCII. It's the
Apex'i SAFC2 
That is actually a great mod no matter what, and the best pick on your list, (if that's what you meant)so I voted this. If the poll had "other", I would pick that.