Personally, wet trackdays are no fun for me, but if you are racing and have to be on the track in the wet then...
Try this :
"Whether you are on the race track or out for a days scratching, soggy leathers are not comfortable, they restrict movement and increase your weight value by soaking up the rain.
The Respro® Slick™ wet weather racing suit is made from stretch Lycra® with a shiny waterproof coating and keeps the rain from being absorbed into your leathers. The tight fitting Slick™ is designed to stretch over your leathers and fit like a gossamer as opposed to many rain suits/jackets that flap about when any speed other than tortoise warp factor is achieved.
Streamlined, Aerodynamic and curiously sexy, the Respro® Slick™ is a must for wet weather riders. "