Anyone have a good link that explains modification restrictions for Solo II autocross classes? I've read the manual, but I'm a bit unsure on some things. I'm not sure what options I have between A stock and STX, but I know I don't want to be modding what I can't use on the weekend.

Thanks in advance.

 

You'd be running in STU. But as far as AS, you basically can only do the following:

Adjustable shocks
Drop in air filter
Cat back exhaust
R compound tires
Wheels must be the same diameter and width. The offset cannot exceed 1/4" (6.35mm) from the stock offset.

There are other things you can do (harnesses, etc) but they don't particularly improve performance. My recommendation is to learn/appreciate the stock car. Just get an alignment and go straight into STU because the PAX index is better.

 

You can get an alignment in A-stock as well.

Like markpaco sai, you'd be in STU. STU allows you to do this:
- intake
- exhaust (full TBE, but you must retain a cat)
- coilovers or springs/struts
- sway bars
- camber/caster plates
- change wheels
- ss DOT brake lines
- brake pads
- big brake kit
- some aero mods
- no lightening mods
- retune FUEL maps only (no boost modifications, so no boost controllers, boost control in the ECU, etc.)

However, you are limited to a street tire with 140 tread rating or higher and 245 max width.


The "next" step is BSP (this is just the main difference between STU and BSP):
- engine remap/boost control is allowed
- R compound tires
- NO big brake kits
- no tire width limitations


Personally, I feel that the X is NOT competitive in a competitive AS class but it competitive in a strong STU class. If you are running in a PAX class (like Novice) then, even bone stock, STU is a better class to run in.


Scroll down on the main index to the Motorsports section. There's lots of info.