You should be OK using the PTs from the mid 2000's or even earlier. The last time the LSAT substantively changed (to my knowledge) was in 2007 when the Comparative Reading was introduced. Other than that, the test has stayed mostly the same throughout the years.

I've gotten 100% a few times. I think the key is that marking up is a tool for me to help remember what I thought was important. I do mark up main points, causation, concessions, exceptions etc. But I almost never refer back to them. I think connecting mental skills (memory) to motor skills (underlining/circling) helps to stick the important stuff in your memory for when you encounter the questions.

In the end, it should still be MINIMAL underling/marking. This method wouldn't work if you underlined the entire passage.

Also, make sure to really hone in on question types you consistently get wrong. I notice that I have a particular problem with "the role x plays in the passage is..." so I consciously focus on that as a result. You may have other challenges and you should enter the passage with that in mind.

Looks like it is from Princeton Review (see below). As far as I know, PowerScore uses all real LSAT material.

http://books.google.com/books?id=canLFRIwKqsC&pg=PA25&lpg=PA25&dq=pepper+picking+pep+rally+lsat&source=bl&ots=Rt6pGeuL5-&sig=807MprvLg4hnPUxHLXIpwrl-7rU&hl=en&sa=X&ei=kPYuVNyHB8-3ogShs4LIDg&ved=0CB4Q6AEwAA#v=onepage&q=pepper%20picking%20pep%20rally%20lsat&f=false