headers for a 3.8L buick will be expensive, when i had a 350 rocket in my cutty, the chevy headers were like 175 for the pair with collectors, those were flowtech. the same headers for that car but since it was an oldsmobile engine, were 375 for just the headers and gaskets, no collector, it sucks with oddball stuff like that, the 3.8L may be common but the header application isnt. think about a 350 and save yourself some headaches with performance parts. 
