I am building a ron champion with 1600 crossflow and weber 32dfm carb fitted but not sure what type of air filter i need !Whatever i use will probably stick out above the bonnet because i prefer that to a bonnet bulge . so can anybody recommend me a filter ? If it sticks out above the bonnet it would need to be waterproof in case i got caught out in a shower . thanks - nick

shouldnt be a problem if it rains I have run Twin 40's with K+Ns and bike carbs with foam filter stuck out of the bonnet with no problems

A bit of water helps, having a torrent fill the carb while parked won't.
Basically if your moving or running the engine a bit of rain is fine.
Something like a piper cross with foam top is probably best for good airflow.
There is an adaptor that fits on the carb and allows you to duct air from a nosecone filter.