Sold!
LOL, I agree with you that the S-Line is the best sound you can get for the 458 (I had it on my old car), but Novitec is FAR from a "dirty" sound. In fact, it's a more refined version of the S-Line sound (my S-Line had a resonant "warble" crossing through 2.5k RPM). Novitec is maybe 2-5% quieter, but clean throughout the entire range. It has the "F1 sound" in spades. It adds valves, so it may even be a better choice for some (not for me; I wanted the most extreme sound at all times). I had Novitec on my car, too, and speak from extensive experience. Regardless, I love S-Line - it's the best.