Interesting. I see you drive an MBX5, is that correct?
That car has a pronounced push. I used to drive one... and I DID like the handling better without a front bar or with a much smaller front bar. (I bought some "music wire" from the hobby shop and made a bar that was only about a 1.8mm bar.) It made it turn in better.
Tire selection is also important. My favorite tires on that car used to be Panther Komodo Dragons. (Not Komodo Dragon II) However, some of the newer tire designs may be better. I haven't driven it with AKA Cityblocks for example- I stopped running buggy and changed to truggy LONG before those were released. Note that our track was rough, loose, and dusty.
If the track is loose and dusty, you don't want a small pin tire like a Holeshot.
ProLine Crimefighters are good tires, but, on a bumpy track they can catch a rut due to the flat profile. Bowties are better in those conditions.
(Note the similarities in design of the Komodo Dragon and the Bowties... somewhat rounded tire profile, relatively large "pins" on the tread.) For the conditions you describe, look for tires with those features.
On a bumpy track it is better to have the suspension as soft as you can run it without bottoming out... it will give you more traction... BUT, too soft will bottom out and make things worse.
And to help that Mugen turn... maybe 5k front, 5k center (7k is ok but will make the car more aggressive) and 1k or 2k rear. 3k in the front would give more steering, but sacrifice some traction on exit from the corner.