whistling injection pump.

[lost on my vstrom]

Hi having problems with my injection pump 08 650 vstrom , originally having a power restriction rev limit which gradually
 got worse down to 35mph on the run into the garage for servicing, this symptom came  back after 3 months and again restricted power so fitted new pattern injection pump / filter  , this started whistling after a while so original was refitted with a new fuel filter, at the bottom of pump for my  France trip  . this lasted until 2 miles from home and  gradually lost power again,.
new pump brought and was fine for a few days then the whitelisting started again , full power, just the constant whistling again make's the bike one ride able due to the noise , and yes I do  use ear plugs all the time   .. hi pressure filter has been back flushed and blown out with air line every time ,new regulator fitted  along with new pump seals .. don't like the idea of drilling the fuel filter , any suggestions .

[Gert]

Was the replacement pump an OEM replacement part from Suzuki or was it an aftermarket part, like for example a Quantum EFI fuel pump?
Either way, if it where me, I would first do a fuel flow test, https://www.v-strom.co.uk/smf/index.php?topic=28671.0 Followed by checking the pumped fuel for any signs of contamination. Leave the pumped fuel stand for awhile to see whether any separation or dirt present.
Also check that the sound is not coming from the fuel cap vent.