6squirrels

I have a metallic noise coming from the engine that increases with RPM .
Car is a 987 Boxster with 62,000 miles on it .
I replaced the serpentine belt a year ago at 57,000 miles .
The noise really gets loud at 3000 rpm and rises slowly through to redline .
The noise definitely is from the engine compartment rather than tire noise .
Has anyone actually diagnosed a noise like this and determined the culprit ?
I know the water pump is often mentioned but I would like to know from someone that has had the same ailment and made the correct repair .
Base 2.7 with the 5 speed manual .
Has not been run hard and has had regular maintenance from birth .
Who has had this and what was the remedy ?