I recorded the my normal springs in my Xotic guitar, then "raw vintage" springs and there is a difference..I think the 'raw vintage" give the guitar more fat, bottom end. And more sustain....everywhere. Cool.
Allen Hinds Web Site

Although with some doubt, I used 5 springs as suggested. I actually have not plugged into the amp yet but I can already feel the difference • It's fat! It's loud! Until now, I used 3 springs.
My SRV Stratocaster has RV saddle and I actually had the original spring changed to Callaham spring. And now with this RV saddle's D spring, I have amazing tone!
Until I read this instruction letter, I never thought 5 springs would be better.

Raw Vintage has a new product "Tremolo Springs". I changed my springs as soon as I heard how it would better the tone. Once I had 5 springs attached, the whole body started resonating differently.
And connected to the amp, the sound was fatter, transforming dry sound into greasy tone, and more volume as well! I was truly amazed what a difference these springs can make.
Springs were put into my Xotic's custom made Stratocaster. My students at GIT (Musician's Institute) noticed the difference after hearing my guitar in class. They were surprised how fat my sound was and asked me, "Your guitar has a different tone today. Did you change the pickups?"
If you use a Stratocaster-type guitar, I would recommend trying this Raw Vintage Tremolo Springs first if you are considering changing your pickups. With these springs, you will be able to change your sound at low cost.

I had those springs put on my guitar and I have to say, to my surpruse "It really makes a difference!!!"
There is a new kind of "resonance" in my guitar!! It almost feels like there is some sort of inner reverb!!??
Very nice, very fresh, makes my guitar and my sound "sing" a bit more!!!!!!! Thank you very much!!
Jeff Richman Web Site

Raw Vintage saddles and tremolo springs made my guitars much more resonant, took out the metal harshness and added deepness with extra air to the sound. Notes got better balances through out the entire fretboard, include open position.
Restored the original tone On my '63 Fender (Raw Vintage replaced generic parts which I put after the original had worn out), and added extra Phatness!
Gave my newer custom Stratocaster a broken-in feel and sound, closer to vintage.
This is one of the best upgrade I ever done to my guitars. Check them out!
Masa Shimizu my space

I have known the little secret of putting 5 springs on the strat tremolo for a long time in order to increase the sustain of the guitar. However to me there was always a trade off with that scenario. I would achieve better sustain however it will come with harsh upper mids that would bother me sound wise. Also the tension would increase so tremolo would become useless. If I would back off with the 2 pivot screws to adjust the proper tension of the springs, then the tension would be right but the upper mid harshness would still be present and the whole process would be kind of a trade off and not quite right.

I was pleasantly surprised when I have put Raw Vintage tremolo springs in it for few key reasons: One, I didn't know what to expect and was kind of sceptical at first. Second the lower tension of the springs allowed me to put 5 springs instead of standard 3 that I would have in my guitars and those 5 springs would have aprox. the same tension as the original 3. Now here is what came as a total shocking surprise, the tone itself was waaaay fuller, richer and there was a lot more sustain gained on my guitar. Fundamental notes were simply fuller, deeper, richer and there wasn't any unusual upper midrange harshness present at all. This is simply the most amazing improvement tonal wise on a strat that one can do and benefit for ridiculous marginal amount of money. But money on aside, even if it costed few hundred dollars it would be worth spending considering the dramatic improvement in tone!
This Raw vVntage springs make a world of difference! I am a believer! Damir Simic Shime
Damir Simic Shime Web Site