Thank you for sharing this video!
I'm very excited to try out this mod. Though while I want a easier to close frunk, I don't think being able to close with two fingers is what I need, and part of me do worry about safety aspects with such a light spring. Also, the suggested spring is 1 7/8" instead of the stock 2.19", and I'd like to see if there are any springs closer to the original length.
Dimensions:
The stock spring in the M3 is 2.19" inner length, with an outer diameter of 0.578 and wire thickness of 0.078", which gives it a spring rate of around 10 to 15 lb/in, depending on type of steel used.
The spring that is used in the video has a wire diameter of 0.025", which has a spring rate of about 0.21lb/in. The spring is stretched a bit more at rest which I assume will bring the rate slightly higher, maybe about 0.25lb/in.
I've just ordered a few springs from Amazon, ranging from 1.5lb/ft to 6lb/ft of spring rate. They're technically much heavier than the 0.21lb/in spring but then it's still way lighter than the stock spring at 10~15lb/in. Their lengths are at 2.25 as it's harder to find 2.19 or 2.125 springs on Amazon. Once I have the weight I like I'll find one closer to 2.19" in length.
The springs should arrive on Tuesday and I'll report back on how they perform.