How much time shaved off with higher spring rates/coilovers? AutoX content.

I've been running my Integra GSR in a local autoX class and having a pretty good time. The ruleset is a good bit less restrictive than SCCA rulesets, with the local classes being mostly dictated by drivetrain type and power-to-weight ratio (which makes for a fun class!). I've been shocked at how well my "heavy" Integra GSR is doing compared to several of the much lighter CRX's (some with B-series motor swaps). I'm essentially running a few tenths behind a couple local leaders in CRX's (0.2 to 0.9 seconds slower, depending) and I'm considering flushing money down the toilet in order to obtain cheap plastic trophies. 

I know the answer is always to drive faster. I'm working on that. In the meantime, I'm not above giving the car a bit of a helping hand. 

My current suspension setup is pretty mild: I'm running a set of OEM Integra Type R springs (250/250 lbs/in springs, with the rears being progressive) mounted to a simple set of OTS Koni yellows. With the shocks around 75% stiff, on the street, I would refer to this setup as just about perfect. Just firm enough to be playful and give a good sense of control, but compliant enough to soak up many miles without wearing me out. I also love the current balance of the car- I'm running a Progressive 22mm rear sway bar (same diameter as OEM Type R) and full Hardrace hardened rubber bushings at all corners. The car rotates nicely, hiding it's FWD nature well and with some camber (via Hardrace arms), it's a very fun car on a canyon road, or even just around town! I also own an AP2 S2000 and refer to the Integra as feeling like "a FWD S2000". 

At an autoX, the car is very well balanced and easy to drive... but even with the shocks at full stiff, there's a bit of roll and the transitions could be a bit quicker. I'm thinking about spending money (likely in the direction of Fortune Auto 500 or 510's) to reduce body roll. I have been considering spring rates in the 500/450 range. I know some people go much higher, but I think this is likely about the highest I'm willing to go on a car that will still see street time. 

My question is: before I go burning through cash, how much of a difference will I likely see on an autoX course? Does anyone have any direct before/after comparisons when making a similar switch? 

I'm at the point where I'm trying to figure out if I can justify the cost to myself. If it's likely to only pick up a tenth or 2, I'll likely save my money, but for 0.5+ seconds, there's a good chance I can justify the cost to myself. I know there's no exact way to determine how much (if any) time will be saved making the switch, as there are too many factors, but I'm looking for similar experiences from GRM'ers, to gain a rough idea on what I should reasonably be able to expect. Any insight or experience is greatly appreciated! 

Thanks in advance! 

A couple of thoughts:

Springs are cheap you could try them and see.

BUT.........why are the CRXs faster? Is it car? Is it driver etc.?

Can you get more out of the car with some adjustments?

Tell me about tires.  What about removing weight?  You may get the time you are looking for but you may not.  I'm not convinced body roll is all bad.  

Tires matter the most after driver mods. What tires are you running now? Are you limited to 200TW?

The class is limited to 200tw tires and width can be no more than 20mm wider than stock, or 215mm, whichever is higher. So essentially, everyone is limited to 205 wide tires (technically, 215's would be allowed, but all the sticky compounds are at 205 or 225). So, everyone is running 205 wide 200tw tires. 
 

The rules read that the car is supposed to be in street trim, showing up in a stripped out car is a no-go. I can save some weight in a few places (remove AC, lighter hood/trunk, lighter seats, etc), but I'm hesitant to go too far into weight savings, as I actually like driving the car on a regular basis on the street. 
 

One of the guys that's faster than me has a shelf full of trophies from SCCA Nationals in STS. He's fast and extremely consistent. I'm sure he's faster than me. 
 

The other guy, we're neck and neck, despite him being in a 500 lbs lighter car, with a better power/weight ratio (he has a B20=more torque than my stock B18c1) and more aggressive suspension setup on the same sized 205 wide 200tw tires. In a similarly setup car, I'm 99% sure I am faster than him. 

In reply to roninsoldier83 :

Where are the areas you feel the car is loosing out?

I seem to recall the Koni Yellow do not have a separate rebound adjustment. Some better dampers with separate compression and rebound damping adjustments may be worth trying

Can you get more aggressive on the alignment settings, specifically the toe?

You can always try some stiffer springs and see if they benefit you.

My first action would be to write down the places you believe you are loosing time and exactly what the car is doing at that moment. From there I would list all the things you can do to  improve that.

After that you'll need to do some testing.

In reply to Tom1200 :

The car feels sloppy on medium-higher speed slaloms, specifically. The transitions back and forth seem a bit exaggerated, I can feel the delay after turning the wheel, which leaves me feeling a step behind.