Our fabricators don't weld on top of welds, that'd be a bit silly although they do weld them a bit hotter than I'd like but it's all to ensure good penetration.
Nobody claimed it was drone free. There's some drone in the lower rpms when there's too much load on the engine, like any aftermarket exhaust has
Anyone who claims their exhaust doesn't have drone clearly misunderstands what drone is. The easiest way to avoid the drone is to not stick it in 6th when driving 40mph.