SCCA Street Rules Question

I don't run my Cobb Rear Motor Mount (RMM) on Fiesta ST for autocross competition because I run in H Street, but I wonder if I am being overly paranoid? The rules say:

Alternate components which are normally expendable and considered replacement parts (e.g., engine and wheel bearings, seals, gaskets, filters, belts, bolts, bulbs, batteries, brake rotors, clutch discs, pressure plates, suspension bushings, drivetrain mounts, fenders, trim pieces, fuel filler caps, etc.) may be used provided they are essentially identical to the standard parts (e.g., have the same type, size, hardness, weight, material, etc.), are used in the same location, and provide no performance benefit.

A RMM falls under drivetrain mounts, it mounts in the same location and is essentially identical to the standard part (weight, dimension) but the hardness is a question. I actually have no idea if it is harder or softer, but I assume it is different because why would they sell it if it didn't? As for performance benefit, I don't feel that it makes any real difference, but it is sold as a way to improve traction.

Anyone have any experience with motor mounts in Street class? Should I keep it off until the season is over again?

I would say keep it off until the season is over. I would think it would fail to pass as it is a performance improvement, however slight. Could be an easy protest if someone wanted to.

I think this is why they specifically say "hardness" in the rules description. Leave it off for competition if you are a front runner. If you're not competitive in your class I wouldn't worry about it.

There is no way that is legal for street.

The rule says essentially identical and includes hardness and materials. The hardness of the bushings is obviously different since on the Coob site it makes reference to the durometer of the two new bushings they use and it says right on the Cobb site that it improves performance of the car eliminating wheel hop and improving traction. Even if you somehow get past the hardness issue, that language right there that means you can't use it.

Even in cases where upgraded materials are allowed in street it's almost always to fix an issue with the particular car and the fix gives no performance advantage.

Thanks, I figured I would be safe rather than sorry. I am heading to a Match Tour and if by some miracle I do better than a-millionth place, I don't want anything to screw it up!

FWIW, I used to run one in my Mazda2 locally, I just used to ask the others in the class if they cared and took a bump to STF if they did. We had a lot of gentleman's agreements at the very low end of the field. I did remove it for national level rallycross.