I have the full dual Librands system on mine and it sounds nice but not too intrusive when cruising, it was fitted from new.

My first 1994 +8 had a standard single side and taking that as the benchmark the Librands is about 5 times as loud and possibly liberates a couple more horses.

http://www.librands.co.uk/products-view-96.html

2009 4/4 Sport Henrietta
1999 Indigo Blue +8
2009 4/4 Sport Green prev
1993 Con Green +8 prev