1) Throttle Body Spacers stopped being useful when carburetors went away (unless you plan to fit it as a port for Nitrous). Spacers are absolute Snake oil, and don't trust anyone who sells or recommends them for a fuel injected vehicle.
2) A ported throttle body can be a good addition if you have the other bolt-ons to go with it. Its C&C milled so that at idle its stock, but as you increase throttle demand the diameter increases until at WOT you are at 85 or 87mm depending on the one you bought. Ported TBs do not require tuning and operate like stock until you get to high demand. Things like headers benefit from a ported TB, but there is not much benefit on a stock engine.
3) A constant diameter wider throttle body is of no value until you get into high air demand modifications (blowers, nitrous etc). That needs tuning at idle and you haven't added any air demand yet.
4) A tuner is best bang for a lot of bucks. Its a pain in the butt vis-a-vis warranty and dealer visits, but yours is off warranty now so going straight to custom tuning is an option.
5) Its a bit of an ongoing debate on this Forum, but I believe you get a little something (and some under hood varoom) with a cold air induction (CAI). The Vararam air grabber also provides a bit of ram air effect as you accelerate. K&N. AFE, and Airaid are just open top hot air noise makers. S&B, and Volant are enclosed and do provide cold air (Mopar makes an enclosed one too). You could also start cheaper with a drop in filter.
6) A lighter and freer-flowing muffler would also be a good first step. The OEM muffler is a massive boat anchor and is chambered which is no bueno. Just reducing weight by ditching the OEM beast would help, but free flowing exhaust does help and you can add a little growl too. Exhaust is kind of a personal choice, so check You-tube and listen to clips and then ignore what everyone else says and buy what you will be happy with.
7) PCV waste Catch Can. A Catch Can wont add a lick of HP or MPG, but keeps some seriously nasty varnish producing blow-by yiltch out of your intake manifold and off your intake valves and TB.
8) Standard plugs seem to work best on these engines. Make sure all 16 have been changed within the last 30K miles. Coil packs and injectors wont make much difference until you bolt on the other performance stuff first, unless the existing ones are suspect.
9) I don't have one (yet) but the pedal commander is a very popular modification that takes the lag out of your accelerator pedal. That to me would be a really good place to start.
Happy modifications!
