Soooo how bad is it to red line an old Boxster?

[thstone]

158K miles is a lot of miles. Your engine is definitely a senior citizen.

Your current driving style will have very little to do with the remaining longevity of the engine. What matters the most is how it was treated the previous 158K miles. If the engine was hammered on for years and years, driving calmly now won't matter much as whatever wear it experienced can't be undone. And if it was driven by a little old lady who never revved it over 3K rpm, then an occasional run up to redline isn't going to matter much.

My advice is to enjoy it and if that means the occasional run up to redline, then so be it.

Starting with a used 90K mile engine, my engines experience more than 3,000 runs up to redline each year on the race track (4 upshifts per lap x 10 laps x 4 sessions x 20 days). At this level of use (abuse?), an engine lasts 2 years. Then I install another used engine and keep going. I'm on Engine #5.