The videos online are rubbish, its either full systems which Im not going to buy ( often with new manifolds as well ) or they are just sitting revving a tiny bit.
If it's any help, I've got the eisenman race back boxes which have amplified the car sound without taking anything away from the s54 sound. No x pipe - just the back boxes. I know we have different cars /engines but don't discount eisenman. They also look fab too.