Has anybody had to replace there exhaust system.And if if so was it aftermarket and what type.Been looking at 4 into 1 but not sure if thats the way to go.Seen a system for a 650 maxim on ebay more of a 2 into 1 srait pipe no manafold under the bike.Or even a good sounding slip on muffler.Any idea´s would be helpful..thanks