The actual change
you see can be quite different to the actual change
I might see from exactly the same change in pressure Pete, it all comes down to the collective impact of ALL the variables involved, including things like the ambient temp, the road surface temp, how hard you ride, how hard you brake, the load you are carrying, the pressure variation, and a whole bunch more.... Buuuut, the only proof is in the pudding, and seriously, you might be surprised how much difference just a little change can bring - so why not try it and see?! And if you think it still feels a 'little loose' on your first try, give it a bit of a chance - for some, it can take 500 miles
or more of ryding to get used to the differences in steering a Spyder, and even just a 2psi change CAN bring about just as much of a significant difference in tire behaviour & traction, ride, or handling, so you might need to give it much the same sort of distance/time to get used to the changes there too!!
Still, you don't HAVE to do it all at once!! You noticed the differences dropping your rear tire pressure down to 20 psi made in ride & handling didn't you?? You should've been quite aware of the difference it made in traction if you ever got to ride on a wet road! So even if you don't want to go the whole hog and aim for that 4psi increase first up, maybe take a few little nibbles at it & get comfortable with a few small differences staged over time rather than one big difference all at once?!? Try it, you might be surprised!
Nb: I usually run 16psi in my rear tire when I'm ryding solo, sometimes even going down to 14 psi if it's cold and wet & I don't want to hang the tail on every corner!! I usually only go as high as 18psi when the Missus is on the back or I'm looking at ryding solo at speeds up over 140kph when it's hot & I hafta do the Alice to Darwin run by tomorrow morning OR ELSE!! But that's what works for ME, and it might not be what works for you.... after all Pete, there's a pretty good chance that you might put just a little more load on your Spyder tires than I do (I'm just a lightweight @ 180cm's tall these days!) so you running a little higher pressure may still see the sidewalls flexing enough to heat things up enough to make for the necessary pressure increase, even if it's a larger increase than I'd see.... make sense? :dontknow:
Still, if you like how it feels at 20psi and the traction, ride, & handling at that pressure works OK for you, then ride at that pressure - just bear in mind that you could probably get better traction & tire life going a little lower. But once you are aware that the 1.5 psi increase you get at 20 psi is a touch less than optimum, and by not making that change you will be compromising your tires best traction, ride, handling, and life etc, & maybe increasing your risk of punctures from road hazards & debris a tad too, then you can make an informed choice. No-one is twisting your arm, altho we might flap our gums or throw a few posts at you for being a wimp & not giving it a try,
especially if you post about traction concerns or short tire life

but ultimately, it IS YOUR choice - we are just trying to make sure that you know about the potential safety aspects, risks, & limitations you might be creating for yourself by running pressures a little too high! :thumbup:
It's those people running tire pressures that are a LOT too high that generally score the long and narrow pieces of mind from Mike'n Me! :banghead: :banghead: