Well I wouldn't be me if I didn't chime in with my $0.02.
You have a lot to do for SUSTAINED high speed racing. Real suspension is your first priority (since by your earlier statement I am to assume you have safety equipment taken car of). If money is no object, visit the 3R Racing website and buy one of everything for the SRT-4.
Since that isn't too likely a scenario, try these things:
1-Full poly bushing for all suspension components. You may want to go to the solid LCA bushing from www.Rage-Tek.com
2-Big Sway bars - Hotchkis are the best value.
3-Coilovers - Many people like the Mopar and KW kits. Personally I went to Koni and had them make me a custom set-up with race inserts into a stock housing.
4-Stiff springs I went 440/660 Eibach's Fr/Rr
Tires and Wheels
1 - High quality 17*8 of your choice. I have OZ's and love them.
2 - High quality 225 to 245 tire of your choice.
is hard to beat for both of these items.
Next I would address reliability issues for the long runs.
1- Lower temp thermostat. 180* or 160*
2- Thicker radiator
3- BFMIC - I would go AIS or AGP Race
Of course to win in any race class, a bigger turbo is always fun!
Mopar Stage 3R (Tial wheel) with Toys. This and basic bolt on's will give you about 350-360 HP/TQ to the wheels. Contact Ted at www.MoparSuperCenter.com
For the extra power you will also need at least:
1-60MM throttle body
2-Full 3" Turbo back exhaust system (see Scott at www.MaxxFab.com
for the best products - I would go with the Side Exit (no cat, w/res)
Of course to stop all that extra power you will need some brakes. For road course braking (frequent and very hard) I went with a Wilwood BBK (Plus 3 or 4) from Todd at www.tceperformanceproducts.com
, but for a direct fit system you can look to Ted again at www.MoparSuperCenter.com
for their custom brake kits for the SRT-4
Next would be aerodynamics....
Lose the factory wing and get one that does something.... I hear Realtime Racing has some nice stuff.
For underbody, I would contact Mark at www.RamseyFamilyRacing.com
in Sanford FL, they are developing a lot of new products to help make the SRT-4 as slippery as possible.
Hope some of this helps....