I've been thinking about some custom seats to replace the factory units.
Has anyone had any experience with any sports or racing seats? I'd like
some pro and con if possible. I'm looking for more side support especially
in the twisties.

http://on-trackperformance.com/recaro_sport.htm

Here is an example in a Cobra R.

 

Sorry I didn't see this post sooner, If you are considering replacing the seats, there are many hurdles you must get by. 1) Mount brackets. 2) Side Airbags-if your car is so equipped. 3)Passenger seat occupation class sensor. These are the three that immediately come to mind. You might try to contact the guys at Redinetuning.com as they are Recaro dealers, they might be of assistance.

Good luck to you.