SC plug changes aren't all that bad. You just do it from below, like you would a third-gen F-body.
Having lived with an SC for a few years, and several hundred thousand miles, I can say it is a superior road car to a GN. In fact it's not even close, and it shouldn't be as the target market was different. The SC was aimed at the BMW 6 series back in the day so that gives you an idea of what one would drive like. BTW, avoid the AOD versions. The factory programming of the AOD is not sporting in the least, and sucks all the fun out of driving one.
The downside is that the thing resists attempts to improve power tooth and nail. Just getting 13's seems to cost a couple-three thousand, and if you want more you better knock over a bank. The highest HP SC at the moment is 440rwhp with an Autorotor blower (think Kenne-Bell type) Worse, the five speed versions wheel hop badly due to a combination of the differential bushings and rear subframe-to-body bushings. Interestingly, the automatics don't do that. All in all they're not drag racers. A modded GN will kill one on the strip at considerably less money.
On the road is where a good SC shines, and makes a GN seem like a buckboard wagon in comparison, So if you want a fun car that'll get on down the road and go around a corner without scaring you to death, along with a certain anonymity (read: not likely to get ripped off everywhere you go, so you can take it places, like dinner, etc.) then the SC is a good choice. If you're wanting to go drag racing, and have the quickest ET around, then the SC is not what you'd want to start with.
(Oh BTW, if you do buy one and need parts, You'll find that there are usually two choices, one less expensive and one more expensive and having to be ordered. You can guess which one the SC takes
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