Aparently beanies can lead to internal bearing damage if left on and raced with. No idea how. Hpc coating increases thermal efficiency in the turbo which leads to better response. Plus if you hpc coat it silver the chicks will flock... hard. But in all seriousness when I do go a steampipe manifold ill be hpc coating the manifold and turbo housing. Looks good, doesn't get that rusted look from heat, serves a purpose.