Will springs slow you down?
I'm running the Tanabe GF210 springs on my Evo along with the Cusco Version 2 lower arm brace. The drop on the springs is 1.5" front, 1" rear. They feel good. 
On the street, the ride is noticeably a little stiffer in comparison to stock. Turn-in at lower speeds (say under 20mph) isn't as crisp, but is most likely attributed to my more aggressive alignment settings … -2 deg. camber front, -1 deg. camber rear, 0 toe all around. Body roll is also reduced.
Now on the track is where I noticed most of the differences…
Turn-in is just as crisp as from the factory. The reduction in body-roll quickens weight transfer and inspires more confidence in the car's agility. The biggest thing I noticed for myself was that some of the understeer was dialed out, making the car feel more neutral through turns and easier to rotate in tighter corners. I'd much rather deal with oversteer than understeer. The car still settles nicely and maintains a predictable poise through sweepers and reducing-radius turns.
Granted, I realize these springs are putting more stress on the stock struts, but I wanted to see if spending around $200 would improve the car's handling at the track. It was a cheap improvement and will keep me happy until I decide to fork out the spare change for a set of coilovers. So far, I dig 'em.
On the street, the ride is noticeably a little stiffer in comparison to stock. Turn-in at lower speeds (say under 20mph) isn't as crisp, but is most likely attributed to my more aggressive alignment settings … -2 deg. camber front, -1 deg. camber rear, 0 toe all around. Body roll is also reduced.
Now on the track is where I noticed most of the differences…
Turn-in is just as crisp as from the factory. The reduction in body-roll quickens weight transfer and inspires more confidence in the car's agility. The biggest thing I noticed for myself was that some of the understeer was dialed out, making the car feel more neutral through turns and easier to rotate in tighter corners. I'd much rather deal with oversteer than understeer. The car still settles nicely and maintains a predictable poise through sweepers and reducing-radius turns.
Granted, I realize these springs are putting more stress on the stock struts, but I wanted to see if spending around $200 would improve the car's handling at the track. It was a cheap improvement and will keep me happy until I decide to fork out the spare change for a set of coilovers. So far, I dig 'em.
I really have no comparison for you as far as slower or faster. I started autox-ing after having the spring/bilstein combo done. However I can say that a a good spring, and you can search for that, has alot of other benefits. I run the Works Ride/bilstein combo, and noticed improved handling all around. Turn-ins are more precise and stable, the car is much smoother in the fact that it absorbs bumps better, and body roll is much less than stock. With that said however, I recommend you do the MR bilstein with the stock springs first. There's noticeable improvement there, and the bilsteins can be had cheaply, and revalved later on to your spec...say you get stiffer springs or something. Next is an alignment, something around -1.5 front, and -1.0 to 1.2 in there rear seems well balanced for dd and some track time. See where that takes you before you go further. Coilovers are fine and dandy, but anything under $2000 is complete junk in my opinion. How many sets have gone through the f/s threads? If you wanna do it right with coilovers, go big and get some Ohlins! 