Hi,
Not too much needed for the b4.1.
If you are running on grass / astro, then the following would be a good idea.
Front end, blue / silver AE springs (or go the big bore spring route), oil 35 / 40 with AE no 2 pistons. A heaver bulkhead is advisable on the front, the ghea one is nice, (
http://p-dubracing.co.uk/index.php?m...products_id=12) there are other alternative.
Rear end silver springs (green if wet / low traction) 30wt oil AE no 1 pistons.
You can add weigh between the rear suspension mount and the gear box.
The above should get you a car that is easy to drive, tune from there to how you want the car to react.
MiCk B. :-)