Go to Muffler Land in Tomas MOrato. Dyan kami nagpagawa dati. ganda mag bend ng tubo duon kasi walang kanto. Headers would cost you 3k aluminized tube. Meron din sila compatible na round muffler for the 998s. Look for Roda yung Manager.
Try SMT kung pakopya o kaya Automax Makati meron orig na stage 1 exhaust system UK made, same with mini store 2/F Autohann along President Ave in BF Paranaque