Push down the follower of an empty mag. If is seems "limp" or little resistance, I'd say you have the old springs. My method is not very scientific, but it works. The new extra power springs make the mags much more difficult to push the follower in the same fashion.
If you've ever felt the mag spring pressure on a Kahr PM9 the extra power R9 springs feel exactly the same. In fact, before I found this forum and learned of the extra power springs from Rohrbaugh, I was about to swap in a PM9 mag spring and give it a try. I'd rather use the right part though, which I did, and couldn't be more pleased with the results.
My R9 would FTF on every round fed from the magazine with "old" or stock springs (SN about 1450+/-), with the new extra power ones it's now 100% on WW Silvertip 115 gr and WWB 115 gr ball. What a difference $8 (well, per mag) made!
Please wear safety glasses or your shooting glasses

when installing your new springs - they can get away from you real quick.