So instead of cutting and gutting it I gave Yoshi the benefit of the doubt and made my own, proper 10* merger which starts to open exactly where the stock bridgepipe is (which also effectively lengthens the Yoshi headers by about 50mm) into a 60* merger for the link pipes. All unobstructed smooth transitions and die-ground. It looks like a four year old did the welding but its an elegant shape and looks better on the bike.
Any who, It feels like has more punch down low now, more up top, sounds crisper more everywhere and developes a real note up high. Pretty happy.
The only thing is this yoshi system has 1 1/2" headers going into 2 1/8" link pipes, seems a mismatch in size for a 2 into 2, but just about spot on for a 2 into 1, which will be my next trick i think.

