An *unpublished* study found it helped college students prepping for the LSAT:
http://www.nytimes.com/2012/04/22/magazine/can-you-make-yourself-smarter.html?pagewanted=all&_r=0
To improve on LR, I don't think it is enough just to keep practicing preptests. You need to apply your knowledge of logic to the tests, rather than learn logic from them. Here is a useful link I found http://philosophy.lander.edu/logic/tvs.html
Already at no 1 on Amazon's bestseller list and its not even out yet :D : http://www.latimes.com/books/jacketcopy/la-et-jc-harper-lee-book-topping-chart-20150204-story.html
@ValBerroa Here are some sample chapters from the trainer online... Before I buy anything I like to see what I'm actually getting and see if it'll be beneficial!