The benefit of changing the TM to PWK for me is easy to find the setting parts. In my case, because of the exhaust system was not the stock, I wanted to setup my carb but setting parts for TM28ss which is OEM for SDR, was bit difficult to find. On the other hand, KEIHIN PWK28 was easy to buy as a KX100 OEM carb. so it's bland new, easy to get jets, needle, valve-CA... still affordable.