I have a c/f dash from Stuart Taylor. It seems quite thin and I am wondering whether I should back it with something, e.g. a thin piece of plywood before fixing the instruments.

Definately.

Is it radiused o the lower edge to pass SVA?

I believe the SVA testers give it a bit of a yank too

It has a full radius on the bottom edge doesn't it??

Surely when it's bolten in place it's pretty strong? Try this first before adding wood!! Rather negates the lightness advantages of CF!!

I have a stuart taylor with the CF dash, which yes, is radiused for sva, and yes, does wobble a bit.

The instruments are just on the CF on mine, and it all seems to work fine, but I don't think it would be a problem if you added a thin sheet of plywood, or even just a broom handle in the big groove under the dash where it is radiused (if you see what I mean) to stiffen it a bit.

HTH,
Adam

Thanks for the various replies. The dash has got the radiused bottom edge. I must admit I got it more for looks than light weight, so I will look at adding some stiffening.

Cheers