Susepsion Setup questions - help me balance spring rates, 75 914 with Suby swap Options

[jpnovak]

So, my "now former" GRM Challenge car went under the wrench this weekend for some suspension work. All of my suspension setup is based on 911s. I have a highly developed formula that works well to produce fast, easy to drive and planted cars.

Background: I built a Suby powered Ej20R (TT) 75 914 for the GRM $2010 Challenge. I went in 2011 and managed to blow up the motor at the event. I fixed the car and had plans to go back this year. Budget and time management will not allow for a long tow to FL and back from TX. So, I spent the entry fees on new suspension components.

The car had original bushings that were completely shot. So here is my "new" setup based on used parts buying with the caveat the the car would be for AX use in the challenge. All parts were purchased and I am still under budget for the event should I choose to go.

Weight: car previously weighted 1920# on scales after the swap. Tires are Kumho Victoracers (V700) ; 205 50-15 on 15x6 Rivearas.

Front:
used 911 Boge shock inserts. Good damping. Bolt on.
used 22mm Front 914 torsion bars.
polygraphite/urethane bushings - Turned on a lathe and fit properly. No slop. No friction. No ER budget. (IMG:style_emoticons/default/smile.gif)
NO FRONT SWAY bar. Car did not have one.

Rear:
Used Koni orange adjustable. Set 3 out of 5 turns from soft. I like extra rebound damping for bigger springs. Compression not adjustable.
used 180# Weltmeister progressive springs.
polygraphite/ urethane bushings. Turned on a lathe and then reamed. No slop. No friction. No ER budget. (IMG:style_emoticons/default/smile.gif)
NO Rear sway bar.

Last night I took the car for an initial drive. The car rides so much better than it did with stock 17mm torsion bars and stock rear springs. The new bushings and removal of a-arm, trailing arm friction really helps these cars.

I have not had the car on the track but I have few "test and tune" curves near my house. The car seems to turn in easily. Neutral maintenance throttle mid-corner makes the car tend to oversteer. Otherwise the car felt balanced.

I chose the initial spring rates based on calculated corner weights on the car and the weight distribution. I gained a little weight in front due to the radiator and cooling system. I lost a little weight in the rear since I had to cut the rear trunk to clear the turbo and intercooler setup. The lack of sway bars also factored in.

I think I need to stiffen up the front a bit to dial out a little of the oversteer. I have not yet played with tire pressures.

Here are some of my options.

1. add a front sway bar. I think this might be too much.
2. drop a few PSI in the tires and help balance.
3. 140# rear springs - would this be too much of a drop in spring rate?
4. Balance with tire size. not much room under a stock body car.

Just want to hear your thoughts and experience. I expect that I will have different ideas after I spend a few days behind the wheel and get used to the new setup. I know, I know. There is no substitute for seat time.