Metal internals, buy you know that now. I find the ball diff lasts about one run on RHR astro before it feels like shite or starts slipping and needs tightening. The ball diff runs perfect on low traction tracks, but the astro kills it quickly. I find for astro the gear diff with 5k oil is perfect. I found with 3k you get the unloaded wheel spinning up a bit more, and lower than 3k is just silly, don't do it. I've also tried 7k, but went back to 5k. Not the oil, but the car was off that day, so I just went back to my previous setup.
Breakages. The car is really solid. I've done a few ball ends, on the rear when running long links. I went with a longer turnbuckle which helps stop them breaking. If you have the kit plastic rear hubs, get some spares, I've known them break. I've always had the alloy ones.
I've done one front wishbone, but it had taken some beating to get to that point. I've broken a top upper nose plate after a roll it cracked. I completed the day though with it cracked. I've also broken the front lower nose plate, where the steering cranks screw in. You won't have that problem with the full alloy chassis.
Extras and bling.
B4-415R00 - Aluminum rear hub carrier (Toe-in 0°) for B-MAX2/4:
http://www.rccarshop.co.uk/index.php...-b-max2-4.html
Front alloy bulkhead with brass insert/ or the steel bulkhead or brass if you plan to run the shorty lipo down the centre as Lee Martin does now.
B2-300FLA - B-MAX2MR/RS Front lower suspension mount:
http://www.rccarshop.co.uk/index.php...ion-mount.html
B2-300FLAW - Yokomo Europe 11g Brass Weights for B2-300FLA:
http://www.rccarshop.co.uk/index.php...b2-300fla.html
B2-300FLB - Brass 50g front lower suspension mount (standard):
http://www.rccarshop.co.uk/index.php...-standard.html
B2-300FLS - 45.8g Front Lower Suspension Mount (Steel):
http://www.rccarshop.co.uk/index.php...unt-steel.html
Front upper mount:
http://www.rccarshop.co.uk/index.php...arm-mount.html
B2-201BA - Aluminum steering bell crank
http://www.rccarshop.co.uk/index.php...max2mr-rs.html
This is a none essential nice to have:
B2-118MA - B-MAX2MR Graphite battery holder
http://www.rccarshop.co.uk/index.php...ry-holder.html
I like this:
B2-118BW - Yokomo Europe 50g Under Battery Weight:
http://www.rccarshop.co.uk/index.php...ry-weight.html
The new Yataba Arena springs are the ones to go for for astro/indoor:
http://www.rccarshop.co.uk/index.php...ult/?q=+Yataba
If you are stating with new wheels, you may want to consider going for the hex conversion, as surely any future car will run the same 12mm hex wheels:
B2-HCOV - HEX Wheel Hub Conversion Kit:
http://www.rccarshop.co.uk/index.php...rsion-kit.html
There are lots of new lightening bits out now, which may help if that's your thing.
Alloy idler gears... I found they wear and get noisy, so went back to plastic. Check the topshaft outer bearing regularly and they last well. Leave it and you may find you kill an idler gear.
Hope that helps, it's a great car.