1. Your KKM intake knocks you out of Stock.
2. Your planned Y-pipe, brake mods, and Victoracers knock you out of STS.
If you survey a bunch of veteran "soloists," they will prioritize mods in this order:
1. Tires
2. Suspension
3. Supplemental harness (such as Schroth).
So, here's my humble advice. If you are going to spend over 5 grand on your car,
1. Start with wheels/Tires. Get the lightest wheels you can, regardless of looks. Your street tire choice is a good one, if expensive. I'd go with Falken Azenis, because they are half the price, and just as fast but that's me. Tires are a wear item, and if you can afford new BFG's every year, go for it. As for wheels, I got Kosei K-1's in 16"X7.5" because they are 15.5 lbs and still under $200 a piece. There are some lighter choices but they got too pricey for me. Get the lightest you can afford, as this (along with good tires) will impact acceleration and handling more than any other mod.
2. Put more in the suspension. The BAT kit is nice, but not the ultimate for these purposes. I'd go, at a min, with Koni struts. Terry Haines offers these in a kit with matched springs, but many people pair the Koni's with Eibach, H&R, or Roush springs with good results. If you want to go deeper, get Koni with Ground Control. Deeper yet? Leda.
3. Sway bars? Tough call. Performance wise, everyone swears by the Aussie bar. But we keep hearing about more problems with mounting brackets getting torn up, even when they are reinforced and welded. If you live close to Terry Haines (Michigan), or if you have a fab shop you really trust, go with the Aussie bar. Otherwise, you might consider the BAT rear (actually about 20.5mm) bar with an SVT front (a little smaller than what you have now, to tune out a bit more understeer).
4. Strut braces, YES, but rear before front, if you have to choose. Otherwise do both at once.
5. Motor mounts are a great idea, but I think they may be illegal for us to change. Not sure on this.
6. Your other suspension plans will help, also.
7. Brakes: If you plan to stay in STS (and I suggest you do, for now) you have to keep the stock sized 260mm rotors. These should work fine for autox, but you will probably want to upgrade your pad material. Mintex 1144, Porterfield R4S, EBC Greenstuff, Performance Friction Carbon Metallic Street. Search the brakes forum and form your own opinion. Avoid cross-drilled rotors, as you will not be on course long enough to experience "out-gassing," but you will challenge the heat management capability of your solid rotors. Reducing the total mass of the rotors will only reduce this capability further.
8. Get a Schroth harness. Now that your car handles so damm good, you've got to keep yourself in the seat so you can concentrate on driving.
9. Got money left? Get the Borla for more low-end grunt.
10. Oh yeah, and you may want to do this first, get the DMD. Less chance of blowing a motor that way.
120K miles is nothing. As you are doing all this stuff, remove and replace worn stuff. Maybe have your tranny/clutch looked at, or budget for when they do fail. Engine blows? Replace with a 3.0 and run Street Mod.
