Yes, they do.
You must be lying - have you altered the stack on your car, there is no way such inferior jap engine technology could do such a thing.
Especially straight out the box with no mechanical modifications.
I have, through extensive research with the Vatican (I still speak to Pope John Paul every day) determined the natural resonance of all the parts and with all my special secret squirrel skills produced totally new designs that if implemented woudl enable you to rev your K20 to 8,000 rpm *all day long*.
Of course you will have to put up with your inferior 8,6000 rpm until you can read the book as I dare not actually produce any results or plans because peer review tends to point out that I am talking total bollocks. Much better to drop it into a book were the credulous can find it without the benefit of the queue of people pointing out the bleeding obvious BS it contains.