Can testify as I've had sex with quite a few Asian transsexuals. The majority of their penises are typically between 4 to 5 inches and usually thin. Every now and again you'll meet one who is 6 inches, possibly more. A few I met had thick penises and those really stretched me open!
Thais are packing heat. So slim with sometimes huge cocks. You either see tiny ones or huge ones ( at least compared to "average Asian size" - heck honestly they're even bigger than many White and European guys).