stavros i was told that aiming the pipes to hit the floor ( like a renualt clio 1.2) will help to make the sound of the exhaust seem a little quieter

oh and BMW 5 series boxes are a V shape or the Merc one like johnybravo mentioned

if you need to get the sizes of em ive got a " few " in stock at work i can test diamiters when im back at work for you