I have a question about Dc header. part number: DCS-AHC6507. This header will be good for B16A2 engine ? I can buy it and this header has good price so I'm asking

 

a gsr header will fit a b16

 

The header will almost definitely not be the correct length to bolt to the rest of your exhaust without modification (depending upon what car it's going in and what your exhaust setup is), and isn't going to perform any better than the DC header designed for your application. If you're looking for something with better performance, look into DC's JDM 4-1 (though this will also require some modification to the rest of your exhaust).