Ttech tubes all the way homie, I didn't have to remove any spring in the gen 8 for ttechs it's ready I go. 3.5 is stated stroke length for the gen 8 without the weights but allthough I would love to try them out I haven't gotten around to making an order for them yet. I will though. The gen 8 is just so smooth for color an black and grey. Not my first pick for packing but it's very capable set on no give and an extra volt or two. It's def worth every penny.