Couple Questions on 911 terminology and what certain modifications mean
 

My car came with a spec sheet that the mechanic/owner did to the car. This was done by the prior, prior owner so I am unable to ask a few questions. I'm hoping someone on this board can explain what these modifications mean and their benefits. The guy I bought the car from, put about 10k miles on the car over the last 10 years.

1) Oil Bypass Modification - I have no idea what this means

2) 930 Mainshaft and 1st Gear - why is this good for a normal 915 on a N/A 2.7 engine.

3) Updated 1-2 Slider, guide, and syncro hubs.

The pic below shows all the modifications but the 3 mentioned are the ones that I don't understand.

http://forums.pelicanparts.com/uploa...1337902756.jpg

Boat tail allows the air from a moving piston to get the heck out of the way easier.

911 Boat Tailing.wmv - YouTube

There is an oil bypass mod on youtube that you can search on. I am not sure they tell you the reason for it. Seems the prior prior guy had longevity and strength on his mind. Not a bad thing at all.

Oil bypass mod improves performance of oil pump, helps engine life.