I have an xp that i ran for a lil over a year, maybe 10k miles. And I also have some comp cams 105 # valve springs with about 10 miles on them. Don't be scared about them breaking, these are after that junk batch(I know because I had the junk batch before these and broke one, these look like a whole different spring compared to the old ones.) I'm asking 200$ for the combo.