I am needing to protect under the arches on the car (Stylus) to prevent any stones that flick up from cracking the fibreglass and generally giving it some protection.

I have some of the car builders solution Wunderseal http://www.carbuildersolutions.com/uk/wunderseal-underbody-sealer

however i have not been that impressed with it.

Are there any better products on the market to try?

Thanks

I find Stonechip quite effective. Sprayed on and can be over painted so a nice finish can be achieved. Any carpaint place will have it or find it on Ebay.

Another vote for stonechip

When I built mine years ago I bought some liquid rubber paint from B&Q. Never had any issues with stone damage since and I drive around in the country where those nice farmer types leave all manner of crap on the roads!!!

Decent coating of good quality stone chip/ guard is as good as anything .

Thanks for the responses. Stone chip it is!