I currently have jun 3's and they are VERY reliable. as a matter of fact i drive the car every day to work and u cant even tell any diffrence than the car when it was bone stock!! I do have the entire jun set up with the dual valve springs, valves, retainers, camgears, and even the jun ecu for it all. It did cost a pretty penny { like 4600 with instalation and tuning} but it is all worth it for the power and dependability. My point is that even though there aggressive, they are dependible and wont affect daily driver at all if used with the right setup. And as far as maintanance there is none i have not touched the car other than changing the clutch since then and its been almost 2 yrs.