Your steering rack does not line up the the inboard a-arm mounts. You may want to look into this if you wish to prevent bump steer.

Just a note on the front suspension. If you are using motorcycle shocks, the lever ratio is backwards. The way it is set up, you will only have 1-1.25 inches of travel . Even if you are using a long travel shock, the range of motion at the pivot will only give you <1.2R of useful travel R= pivot to pushrod distance. Did a lot of modeling of inboard pushrod suspension. Ended up going outboard for simplicity. Pushrod works better when designed correctly.

I've actually found that bump steer varies quick insignificantly with steering rack width and inner tie-rod horizontal placement. It's the height that's much more sensitive of an adjustment. If I wanted a "perfect" steering rack width, I would've had to take another two inches out of my rack, which is impossible. But it doesn't make too much difference. Now, if I moved the rack up or down by 1/8", it would've been a pretty significant change in bump steer characteristics.

You're making tons of progress--that's awesome.

Looked at it again. you do have a ~45deg angle on the pushrods. and your lever ratio on the rocker is about 1:1.5 or 1:1.4. That gives you about 1:1 at the shock as you indicated. Most use R6 or R1 shocks that only have about 2 inches of travel. 1.8 to the bump stop and about 2.25 to bottom. If you are using a shock with 4.25" of travel then that is perfect. MY BAD... Should have looked at it more closely before posting. Forgot about the pushrod angle and you are not using motorcycle shocks.

Sorry.. Carry on..

thank you! how about a race to driving? I need some further motivation

yeah, ideally to get zero bump steer in full range you have to have the rack at exactly the right height and exactly the right length side to side.

I gotta think you are going to have noticeable bumpsteer with your current setup because of your overly-long tie rods. How that affects you and your driving is for you to decide, plenty of cars running around with bump steer with the owners still having plenty of fun.

I just noticed the slicks you intend to use, your single element rear upper arm, which I considered below borderline for street tyres, is in no way suitable for those wide slicks. You have 100% torsional loading in the lower arm along with a leverage factor. But it's probably fine as long as you accelerate gently and never, ever touch the brakes....

I don't think that muffler is going to be enough. The S2000 engine is one loud motha.

As far as your bump steer goes I'm betting it won't be bad at all. The longer steering rack rod will give you a longer arc than the suspension arms and in theory should give less variance than if you had shorter rack rod. Most people who have trouble have shorter rack rods which have more arc change in a short distance.