Not on a 1050 but the Black Widow on my 2015 AL4 is pretty good. The noise is higher but sounds nice. You have to use exhaust paste to assemble (provided) - there is no gasket at the join to the link pipe - which can look a bit messy when it comes out around the joints but overall for the price I am impressed. I have the long version as I have luggage fitted.
p.s. the baffle absolutely 'strangles' the output so will only fit it for MOT's.
p.p.s I did notice a little improved pick-up on accelaration upto 4,000RPM, which is nice also.