what they are saying is that there is no "safe" spring or any form of lowering that will keep your stock setups original lifespan. the stock strut was not meant to work under those conditions. there are struts that will work better than your stock pieces, some were metioned beforehand. if you arent doing a major drop, like the small amount you will get with the perrins, then its not completely necessary to swap out your stock struts, they will work, but yet again, will wear much faster under normal everday conditions then with stock springs.and coilover is a bad word since it refers to the fact that the springs are surrounding the strut, and the mcpherson system you all have is technically a coilover system. but the difference youre refering to is a regular lowering spring is just that, a spring that is different than your stock piece, whereas a coilover is an adjustable spring that basically drops in the same way, but is has adjustable height.
I hope ive helped rather than confuse you further. when youre doing something like just lowering your car rather than trying to set it up for a race app. then its a matter of taste and price. you get what you pay for and pay for what you want, not whats available or else you wont be happy. and if you really want to know what a product is capable of doing you should call a vendor and ask them questions about the product, see what they recommend. i dont know who you planned on buying them from but give them a call. im sure they wont mind.
