XRAY - Model racing cars

During the weekend I was trying to work out a way of increasing my rear traction out of a corner, whilst not giving away too much steering.

It seemed that as I was coming onto the power from mid corner to corner exit, the back the slide sideways slightly instead of just pushing forwards.
This was running a Mod on carpet with Ride Rex30 tyres on low-medium grip.

Standard chassis and top deck, no layshaft screws but steering brace in.
Due to the rear being a bit loose mid corner I did run long rear wheelbase and 1.2 rear roll bar.
2.5-2.8 F and 2.6R 400 oil

I tried;
2.3-2.6 rear springs but this just seemed to make the car a bit too lazy
Dropping rear upper link to 1mm on the inside which helped with the 'looseness'

I assume that if I wanted more rear traction out of a corner I need to transfer more weight to the rear on power.
I didn't want to put 2.5 rear springs in as I was worried about losing too much steering and 2.7's are too much for the traction we have.
I also didn't try anti-dive and anti squat as I thought these would also prevent the weight transfer I was after.

Anyone have any advice as to what I could change/should have tried, or is it that I need to straighten the car up more before applying power?
I managed to get within 0.4s of Andy Moore's fastest lap despite all this but I wasn't consistent enough to keep putting those laps in.
Thanks
Skiddins

Did you consider:

Thinner rear diff fluid

Low rear diff position?

I must confess that I didn't consider either of those things
Would having thinner rear diff fluid not cause a loss of traction out of corners?

i had the same issue on a damp but drying amcc track i dropped the rear inner links to 0 shims and cured it,although this was whilst running the lipos down at the end of the meeting,the car is sorted for the next round,that was with 350 oil and 2.6 springs 2nd hole out on tower and only 2mm shims at the bottom shock mount,i still had plenty of steering