[Astromic]

hey guys,
i'm on replacing a 4-1 header to my engine but i don't know if i have to remove the heater box(not a must to me in this weather) and add a "L" pipes or leave the heaterbox, does the heaterbox make a big exhaust restriction or not.
i heared some ppl talking about removing it and then the replacment pipes produces heat under the cyl-head wich is not good, is that right?
i need ur advice before doing anything,
thank's in advance.

Michael