For what it’s worth, I had the 4.2 and very much like you wanted to fit something that freed up that lovely v8 sound.
I bought the OEM MC Corsa exhaust (the one fitted on the 4.7 MC) and because I didn’t fit the after market valves controllers, they ended up always being open.
The sound although fantastic was just too loud and obnoxious to be a daily driver and hearing this ALL the time. I did this for 12months and probably lost some hearing capacity
If I was to do it again, I would go for the same exhaust if the car was just a week end toy, and would go Larini X or H pipe for a daily driver.
My 2p