Had the chance to open up the 1995 Bonneville (with about 150K+miles) tonight. Those sppeds I was talking about above are easy cruising speed. Straight flat ground doing about 80 and no cars between me and the off ramp I was heading towards so I hit it - about 125 MPH before I had to slow for the ramp - Wish I had about two miles, there was plenty of MPH left in that old car 
Feels like it should do a solid 135