...pretty sure it was mentioned several times that they only sound good cammed or with a turbo well before you made this statement.
To ask a question like "I wonder how many people have done (insert any anything to a GP/3800 here)" basically says you're either trolling, or are so newb that you haven't even been born yet. You are waaaaaaaaaaay late to the GP/3800 party. This engine and platform's heyday has come, and has long since passed. This means anything and everything you're thinking of doing, or have done to the car has already been done many, many times over quite a few years before you got your car.
After nearly 2 DECADES of people playing around with these cars/motors, every imaginable combination of exhaust components has been thrown at it. The conclusion is that the only way a non-cammed or turboed 3800 sounds good to someone is if they are inexperienced with how various engines sound, have piss-pour taste (just as ricers think their wet farts sound "bad ass") or are trying to delude themselves. Even the GM 60° V6s (2.8, 3.1, 3100, 3400, 3.4 DOHC, etc) sound infinitely better than their 90°. Throaty at idle, still gargles a bit even at around 3500 RPM, and never hits that monotone 4-banger sounding note that the 3800s have at anything passed idle. I've actually found them to be one of the best sounding V6s. However, even with those, I still called anyone who mistook them for a V8 a moron, so you can only imagine what I think of someone that mistakes the 3800 for a V8.