Try GRD Performance. They're in Naperville and a member on here (Emad - aka, chitownballer - Profile info:
http://www.protege5.com/vbb230/member.php?u=4986) has had some stuff down there.
Actually, last August, we had a meet after a dyno/meet at GRD. They do Audi/VW and Subaru, but they are open to Mazda's and Mazdaspeeds now...Emad knows the owner, etc.
Give them a try:
http://www.grdperformance.com/home.aspx (directions:
http://www.grdperformance.com/directions.aspx)
Hours: Monday - Thursday: 10am - 6pm, Fridays: 10am - 6pm, Saturdays: 10am - 6pm, Sundays:* Closed
Phone number: 630.369.2800
email:
contact@grdperformance.com
Or if you want a general opinion on Chicagoland, try registering and posting over at Chicago Velocity (
http://www.grdperformance.com/home.aspx). I'm sure you'll get some responses - there are a few tuned (FI) owners on there and typically, they're good about sharing info.
Anyway, welcome to the boards (if you haven't been welcome by these hooligans here

) and we'll see ya around!