On icy roads with the stock tires, same thing, look out!
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I think the Regal with the Turbo T package was somewhere around 13 or 14. Seemed like a lot of bang for the buck back then. I don’t remember how much the GN added. Difference was wheels, rear spoiler, interior with bucket seats / center console, badging, etc. as I recall.
GNX had a better turbo with a bit more boost, upgrades in the inter-cooler, ported and polished heads, chip to go with those and, again, different wheels. Interior package and badging, etc. A lot of money for what it amounted to, but I think a lot of it was outsourced.
Something interesting I remember was that you could not get electric seats in a Regal with the Turbo T package. Strange quirk that we never found a reason for. It had 60/40 front seats.
Those cars did have some turbo lag in that era, unlike the superchargers. Sounds like todays are improved!