Possibly switch to lipo packs and consider either the SMC 4000/5000 or Orion 3600/4800 packs that will best fit in your car. NIMHs for local racing are nearly dead in my area. You can potentially lead the way in your country with them. May require you to also get new charger(s) though.
My 12 NIMH 6-cell packs were retired 6 months ago and I get along just fine with only 2 lipo packs.