If I had any kind of performance build, I would consider adjustable rockers a required part, simply because they allow you to equalize the lifter preload. That alone is enough for me, whether or not I could feel or see a performance improvement. Also, if you EVER decide to go to a solid lifter camshaft, guess what? BAM! You already have the rockers. It's just a no brainer to me. I would consider curb feelers, and big stereos "just spending money", but not performance engine parts. That's a good investment.