If you're running a high flow cat I think technically you should be in STX... but I haven't read the rulebook in a while so they may have changed that recently?
^That's all good advice. Intake (use a K&N with the stock intake) and exhaust are kinda the main point of having the ST class. Those are actually good stock, so like he said, work on your handling. Tires & suspension are key. You can have aftermarket wheels so look for something lightweight. Adjustable dampers are nice. Check to see if you can have coilovers, I'm not sure if those are STS legal but if they are and you don't mind a crappy ride that's the way to go. But depending on how long you've done this you may not want to just throw money at your car. If you can get a lot of seat time and learn to drive the stock suspension well, that will make up more time than mods will.
Yes, that is a banana in my pocket.
Dan - gump
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