Don't know but it will take you a looooooooooooong time to get there. On a serious note, I believe I saw something on here about this a while back. Someone was arguing the top speed was a gear limited 107 MPH, but that may have been for the T5.
i had my last 89' hatch auto topped at about 110-115 mph. of course going down a slight decline. i past my buddy in his 96' 318i (bmw) and later he told me his speedo was at about 108-109 mph. this was on stock 14" wheels with a 195/75 tire, and the wind in my favor.