By M471, do you mean Turbo Look? If so, that is M491. The M491 is all Turbo, through and through, except for the engine. I recently sold my own 1989 M491 Cabriolet and I regret it. Having said that, I regret having sold many of my cars, so take that with a grain of salt.
I will tell you that even if my M491 was spectacular, I often wished I had the Turbo engine under the lid. I even considered supercharging it for a moment or two. The things about the M491 that are better than the Turbo are the maintenance cost and reliability (lower and higher for the M491, respectively), and the rarity. I think there were 43 or 48 M491 Cabriolets made in 1989, for example. Here's a picture of my old car for your reference and viewing pleasure.
