I am still learning how to use my HP Tuners here are some rookie questions. Thanks in advance.

1. What is considered the limit of spark advance during WOT? Right now I'm at about 23*-25* through the rpm band. It's a completely stock 4.8 other than tune.

2. What does detonation sound like? I know I can see Knock Retard on the VCM scanner but what does it sound like? Is it a rattling noise?

Thanks.