Since the tank needs to be free of wax/greasy stuff to apply my Stompgrips I want to use white-spirit to clean it but I want to check if this causes troubles with the nylon tank, can you guys help me out?

Another thing, is it true the grips need 3 to 4 days to 'dry' before I use the bike or is just a night enough?

Out of curiosity, why not TechSpec?

A washing with a good detergent (like dishwashing) and warm water should work fine. Be sure to rinse very completely (until surface no longer feels very slippery even when wet). Note that these detergents are also pretty effective at removing waxes; If you use a wax, and wash with a detergent, I suggest a re-application of the wax (yes, the areas where the Stomp Grip isn't )

There are also paint safe "degreasers", which can also be detergent rich. Again, must be rinsed very thoroughly.

I would not use mineral spirits or a Stoddard solvent (= white spirit), as this would leave an oily surface; would require at least a detergent washing regardless, before application of the Stomp Grip.

Slap and dash, should be able to used immediately really. It is a large sticky patch after all.

Remember dish washing liquids contain a lot of salt.

meths dude. (brand alcohol in dutch)
it is only alcohol and eveporates that quickly it can't harm the plastic.
I used it when I put the techspecs on, awsome!
Techspec recommends to do it on a warm tank so the shape of the tank forms nicely in the pads and after that let the glue get to strenght for several hours.
Doesn't need too much time before you ride unless you take it to a track and want to test the pads to full strenght straight away.

Just bought 96% alcohol (4% water) so will use that after clearing the surface with loads of water and a few drops dishwashing soap.

Twisty ride tomorrow to test them.

For any who may read this in future: A caution using ethanols and methanols: A quick wipe is fine, but soaking the surface repeatedly and/or aggressive rubbing of the surface with it, can damage paint finish (e.g. make a matte finish shiny - permanently) , and ultimately remove it altogether. Denatured alcohols (mostly ethanol, cut up to 10% some other methylethyldeath, commonly methanol), as its often used for this purpose specifically (finish removal, solvent, etc.).

Excellent for final surface prep, but just go light and easy.

I took my time cleaning the surface and positioning the grips but they're on the bike and feel solid already. Tomorrow I'll know how much I love them

Had a 350km blast today, love the stompgrips!

Once again, the more you push the SD, the better it behaves!

Oh... You already did that... I would suggested you following forgotten option ...just to have complete palette of different choices

IIRC, stomp grip's instruction says to use........