well, im not a fan of H&S either lol.
Custom work isnt a problem, the issue you have to is proper exhaust design and attention to detail.
For instance, magnex are run of the mill, high output exhausts with not much in the way of innovation or design details.
Even the orbisoud exhausts arent the best made.
The best exhausts are always custom, but only when the person designing, and the people manufacturing have a clear aim and know exactly what each part is going to, not trying to, achieve.