987 3.4 into 986 Boxster S

[tholyoak]

As stated, in order to run the new 3.4 you need to update to the later DME, actually a 7.8.X but the older 7.8 can run it with a custom map.
This isn't a plug and play where you just get the new dme and plug it in, there are other changes that need to be made. On a 2002 they aren't that involved but you have to know what you are doing.

The changes are the same as putting in a 3.6 or 3.8, so to me it really makes no sense to do all the work for a 3.4 that will have minimal gains over the 3.2 that is in the car. That is unless you are getting the 987 3.4 for VERY little money.

If you want to do a non-factory job, you can cobble together a solution with a piggyback controller to control the variocam plus (valve lift) but it isn't a very elegant solution.

The 987/997 engines are not that much more reliable than the 996/986 engines, they are still the M96 based engine. If you buy a reman motor from Porsche it will have all the updates that a newer engine has (revised IMS etc). The new engine in the series 2 997 is a huge update in engine design, stated to cure all the shortcomings of the old M96 motor.
-Todd