Upon taking my XJ in for a service (bought it a few weeks ago), I was told that if she were tested, she'd fail on noise levels, being a few decibels too loud

I have a 4 to 1 with a rather wide can. You can sort of see it here:

So I was wondering if any of you might know?:
1. What was the original exhaust configuration for the XJ 600N in 95 - 96?
2. Would fitting a new baffle quieten the beast's growl a bit?
3. Would a new baffle severely impact her performance?
4. What exhaust do you think this is? There's no branding on it.
I must admit that on longer trips, the noise doers get a bit much, resonating in the ear.
Cheers
/Greywolf