i have the dual exhaust "U" pipes coming in the mail. now, i need glasspacks. which ones do i want? 1 7/8, or 1 3/4? i have 2 links to both. http://store.summitracing.com/partdetail.asp?autofilter=1&part=WLK-24210&N=700+115&autoview=sku http://www.performanceexhaustplus.com/0/0/0/6012/shop_by_category.html -- -jon