A lot of added expense goes into running them. You have to machine clearance in the heads for the extra lift the cam has. Purchasing lifters and then doing the full shimming process takes quite a bit of time. You will have to run a better spring that what JWT suggests. The best spring I've found to use is their hydraulic HD spring they suggest to use with their hydraulic cams. Doing this requires a specific break in procedure and so forth. You need a high zinc content additive for the wear in process. While some here say you don't ever need to check valve lash for every 60K or so that isn't the case. You should check it every 15K as wear patterns material reduction can/does/will happen and the more clearance you run out of spec based on the application the less performance you will see. Running a solid lift application takes a lot of up keep and attention to detail.
The springs suggested severely lack in seat and open pressure and will ultimately send you to valve float prematurely. There just simply isn't enough pressure exerted to maintain control ability in the area. This is the reason why I use the JWT HD springs in place of the ones suggested. The only other springs I would suggest would be the supertech dual coil springs offered for the VG.
