Having the ability to increase the duration of your rocket booster would be fun
1000 credits: additional second
100 credits: additional .1 seconds
(Suggestion made by bugatti)
5000 credits: allows you to turn booster on and off, instead of having no control.
Basically multiply them to get higher increases.
Btw this only affects a single booster, so you’d have to spend more if you wanted to increase a different cars booster
When you apply the booster, an additional menu will appear below it, with the amount of credits you want to spend, and a brief description of the upgrade.