Mine has the TTI 2 1/2". Very quiet. Car runs 12.50s through the full exhaust. Only issue fitting was the reverse rod for the 4 speed needed modification. As far as the stock tips, they are easy to modify. Cut off the small inlets. Oval a piece of 2 1/2" tube very slightly and weld it on. Mine has been this way for 15 years. The exhaust system still looks and functions like new. Although the TTI headers themselves are in need of a recoat this winter.
Doug