So the 318 W/air springs are the same as the 340? Or should I add them to the upgrade list also? And are Poly bushings good for the rear springs(I've heard conflicting reports)?
And Autox... Are those single or double adjustable?
Yes, the 318 W/air springs are the same as the 340. There's not that much difference in rate between them. The 340 T-bars are nothing very special. If you are looking for improved handling and want to buy new T-bars go around .94 or above.
With the other stuff you are doing, go with the 1.00" just suspension T-bar on sale for $179. That will make a huge immediate difference. You will be happy.
Poly rear leaf springs are fine. That's a performance increase, but you have some ride tradeoff. As with most all handling upgrades. The Polys will translate more trunk resonance/noise. Some people run rubber fronts and rear poly as a trade off.
The shock I have are single adjustable QA1's. From what Rocketride said you can get them for $125 EACH.