SDR Valves over Standard

I have read (but now cannot find) that SDRs have 1mm bigger inlet valves than stock SDs.
Can anyone confirm this for sure and are the exhaust valves the same diameter?
Are the stock and SDR valves the same length and are the stems the same diameter?
Thanks

OK. I now know for sure that the SDR inlet valves are 3mm larger than stock.
The SDR valves are titanium but I can't find out if they are the same length.
Other than recutting the valve seats and reprofiling the inlet tracts does anyone know if it is possible to fit SDR valves to an SD?
Anybody?