the gp5k are a bit overrated and expensive. since im not racing anymore i'am tring the conty ultrasport iii.
they feel quite good, even the upgrade from 25 to 28 seems worthy whitout losing performance but the comfy is so damn good
I had some 32c gp5000 on one bike and was AMAZED how good they were. Love those tires.
I had some ultrasport III on my road bike that is limited to 25c (max) and they were okay. I recently switched that bike to gp5000 clinchers and... they were a little better. I was almost disappointed that they weren't THAT much better. Almost. They roll a tiny bit smoother and they have massively more grip in the corners (but, in fairness, my ultrasports might have been a little old/worn). Now that I've done a few more rides and longer rides with them is that I now see that they can they roll faster with lower pressure. At higher pressures that I typically run, you really can't tell much difference except for the extra grip you get on the 5000's in the corners. But, now that I know I can run them 20psi lower and not lose much speed, I might be changing that.