i have 2" headers and i dont know which size system to buy to hook up the rest do i get a 2.5" system or what help pls inow its prob wrong form

 

If you have a header with a 2" collector...which ultimately means you have a motor that isnt a power maker, just get 2" piping. 2.5" inch would be a waste of money and you would still see no power difference over 2" piping. Only reason to get a larger exhaust now, is if you had future intentions of swapping or boosting.

For ***** and giggles it would help a lil if you posted what motor is in the car...

 

http://www.vrsexhaust.com/TUBING_KIT.../honda_tk.html