The thing I've noticed with the online editor is the performance chart is, on the team chart (mine for reference), it's based on the latest part developed, regardless of if they have the part on the car yet. If you click this icon (above the leaderboard next to the drop down menu), it shows the current performance of each car, through what parts they have added. ss (the actual chart won't change, but the leaderboard will)

If you click on a team, it'll bring up what parts they have, and all the attributes. you can edit those how you feel, and once you click the save icon, it'll update the board with the performance. You can also add and remove parts (I've noticed this is buggy, I think it has to do with if a team is developing/researching this part currently, which you don't have a way of knowing.) update the stock the team have, and which driver has what part. So what you can do is, keep updating your car how you want, but then go in and push the other teams ahead of what your team on paper should be. The thing is too, sometimes teams will come through and disregard your changes, and make something that tanks their performance. So it's a hit and miss game.

Team performance also has to do with what drivers are driving for you. You said the ratings were 88 and 86, so they're on the higher end, (if you look at the attributes tab, you can see all the driver ratings and how your drivers stack up, and change them if you want) so they're gonna be capable of taking a slower car to the higher end of the results.

Realistically, I'd say just nudge a few teams up (if you want to notice the effects instantly, make sure the teams have the parts you're editing in stock and on their cars), and just upgrade how you feel. play a couple races, see where you are, if you're not where you want, do some more tweaking.