Genalex Gold Pins vs stock here. GLs are a significant improvement -- more bass, a little more sound stage, a little softer in the treble region (which is a good thing with my Utopia and Auteur, not so much with my planars). In all, to my ears on my equipment, well worth the $70 I spent (15% off ebay deal) since my number one goal with LP was to improve sound from Utopia. From GLs, both Utopia & Auteur produce wonderful bass.
Now I'm looking for a pair for my planars (don't need bass boost, want more treble energy, overall impact). Considering NOS Siemens and Amperex ... $$$
Hope that helps.