UK, Si600's 07 RSVR already has the 40 jet fitted. It's really only the older shape pre 2003.5 bikes that benefit from this.
The issues Si600 has are with the brembo clutch master cylinder self bleed.
Si600, just do a few pumps on the bleed nipple on the master cylinder by the clutch lever, i.e open bleed nipple, pull clutch lever in slowly, tighten bleed nipple, then repeat. You won't need to replace any fluid yet, just be carefull not to get any fluid that escapes on the paintwork. A small towel on the tank would be handy.
Try this first and see if it sorts out the problem