I have read many posts regarding on track use of Factory Five Cars. I purchased the online manuals of both the Challenge Car and the Base Mk4 kit. I also attended the build school for the Roadster. I also reviewed the NASA rules for Challenge Cars, ST2 and 3. I would like a few things confirmed before I step further down the path.

My first group of questions is for Factory Five - I am unable to find a brochure for the challenge car? The online info seems outdated - makes reference to both Bilstein and KONI shocks? The online manual shows the brake installation using the Wilwood pedal box, but the parts list does not include it? Is this model still in production or perhaps the documentation being currently altered?

My use of the car includes both a fair amount of street driving use of many of the tracks on which NASA hosts races. I am not 100% sure I will ever advance to actively racing in the Challenge series, but would like to keep that option open. I am happy with the use of 302 push rod engine with fuel injection. But, this is where I find the rules of the challenge series somewhat restrictive. They state donor parts should be from an 87-93 Mustang. The donor I have is a 97 Mustang for the some of the parts.

If I use the 97 Radiator, Steering Gear, Rear End and Brakes from a 97 does that make the car illegal for class?

Next is the transmission, if I am going to buy a TKO 500 or 600 does it really matter that the 5th gear ratio is .82? The video I watched the Challenge Cars never even used 5th.

And I am really confused on wheels 17X9 and tires 255/40x17 Toyo's is this an absolute or max size? For example if my rain tires were Toyo T1 Sport 225/45X17 on Mustang 17X7.5 stock rims am I illegal?

Lastly are the Trick Flow parts required? It would seem not, I know I would be down on power but it's fine for learning tracks and car handling.

I will either end up with a Mk4 with 302 or a Challenge car with the same motor. So for a car that will see both street and track use which is the better path?