It was recommended that I start a progression thread. I installed the Injen cold air intake on my 3.9 yesterday afternoon. I was worried about it after reading some of the posts about it fitting or not fitting, but it works great!
I did have to buy a longer vacuum hose and cut off the tip of the stock rigid hose to clamp it on. That cost me an extra 5 bucks for the hose and two clamps at Advance Auto Parts.
Also, I started fearing hydro-lock and only installed it as the short ram setup. I've ordered a 3" blue air bypass valve (filter) off ebay to replace the very short 3" hose between the mass air flow sensor and the filter. Once I have that in, I will install the full cold air setup down behind the bumper cover.
I've not noticed any performance gains since installing the intake, but it does sound a bit better. I miss the air sucking sound I used to hear when I let off the gas on my ex's Grand Am. Sounded almost like a blow-off valve. All I had on that was a K&N cone filter on the end of the stock intake.
The only other mods I've made so far are installing the stereo, amp, and subs that I had in my Golf TDI. The stereo actually looks a lot nicer in this car. The only draw-back is a slight hissing sound when no music is playing. I think it's due to the monsoon amp still being active. Has anyone had this problem? I'm thinking about bypassing the stock amp completely.
I finally heard back from Racing Line yesterday. My strut tower brace is still 2-3 weeks out on backorder.