ZL's are EXCELLENT trial machines for the buck, but limited in their big bump capibilities due to softer shock calibration. $3200 is top dollar for a 2001 but not far off for a super clean low mile sled. I own a 2000 ZL600 and love it after making some minor modifications.
1) AD Boivin suspension coupling kit is a must have, if the 2001 does not have rear suspension coupling blocks like the ZR's do (I'm pretty sure the 2001 ZL is not coupled). This kit reduces inside ski lift when accelerating out of corners and eliminates kick-back over bumps. It also adds rear suspension spring rate for heavier rider like me.
$100
2) FOX RACING SHOX front and rear are a must for rough trials and future rebuilds (stock ZL shocks are not rebuildable and wear out quickly). FOX makes a kit specific for the ZL. Give this Shock Therapy in Durand , Mi a call
http://www.shocktherapyracing.com/
$700 for a complete set of four (but two rear shocks are the least you should do).
3) Camoplast Rip Saw 1.25 track. Huge improvement over the stock track if you want to run with the big boys in the trials. I can run with just about anything in the twisty stuff and clean up in the powder.
$350