hi to all sifus..

my friend have a mazda 808 13B rotary engine..the question is i need some advise to all sifus here about the custom air filter for 13B N/A rotary engine carburetor.which 1 is the most suitable that can fix with the stock carburetor that will give better performance(better pickup n top speed).the current setting is hard to get the pickup with the stock air filter..

hope anyone could help..
thanx