I've purchased some Kosei K1s to put slicks on, but I don't know what size to get. Anyone with slicks have some input? Mardigras? Steve? Don?

 

I am running M/T 3019's 22.0/8.0-15 Tubeless. They are only 22" so they will effectively lower your overall gear ratio and you can't beat their stickiness. They are also very light and last forever.
If you are running spray they are the way to go, if you are turbo then you want a larger dia because they build big time on the top end. Not sure on S/C engines.

 

I'm staying N/A so I'll probably go with a short tire like you have.

 

If you are an auto or are going to stay NA I think the 22" slicks are what you need. If you are boosted or juiced you need more tire. Most major slick manufactures strart at 26" wich IMHO is a bit high. I found a company called M&H that offers 15" slicks in 24.5" heights. This is what I am going to try.

http://www.intercotire.com/

 

Neal...so you're going to let me borrow your slicks for a couple runs so that I can actually get a good E.T. right?