The 3.4 is a big improvement over the 2.5, 2.7 and 3.2. It's fast but not scary fast. I'm thinking the improvement difference might be with the intake, exhaust and 996 tune more than the displacement. The 986 is majorly corked on the intake and exhaust over the 996. I'm about to switch back to a 3.2 block because my cam adjusters on the 3.4 are starting to throw chunks of green bits in to the oil. There are some other issues I'm having with the 3.4 and it's just easier to pull the motor. I plan on switching out the intake system and exhaust from my 3.4, and putting it on the 3.2 before installing it in my boxster.
Back story on the 3.2. I bought a flooded 2002 S out of Louisiana last week. It was hard to tell from the pictures how high the water had gone. I've bought many "flood damaged" boxsters before with the only thing wrong was a wet immobilizer. I wasn't so lucky with this one. This one had actually been in a flood. The water had got as high as the bottom of the dash. I checked the dipstick and found moisture. I got it on my lift and pulled the drain plug. For 30 seconds nothing but very clean water came out. Bummer! I decided to pull the sparkplugs and the pan to see what damage might have incurred. 5 of 6 cylinders had water in them and here's with the pan off.
With nothing really to lose because I can't sell this motor, I decided to carry on. I cleaned up what I could and replaced the DME, Immobilizer, key with a spare set. Turned it over a few times to clear out the water and then threw some oil in it. I had to jump the fuel relay because it had corroded. After about 30 seconds it fired up.
