if you have no muff / res you have no business charging 600-700 bux sorry man.. not to mention 2.75 is the absolute largest I would go on a stock turbo vt and even that would be pushing it.. an exhaust that had a 3" dp.. then dropped to 2.75 then tapered down to 2.25-2.5 would probably be best. but since no one would actually make that.. 2.5 is good enough