Upgrading to a better radio is one of those things that so many consider non-glamorous (something new for the car will surely help more!) but it can be a significant upgrade, and *can* help shave time off of your laps. Well, that is, for people using entry-level radios. I tell people stepping up to the 4PL is a worthwhile move, and I can definitely feel the difference when I have to use a low-end radio. I have a 4PK which I bought before the 4PL was available, and I'm sure if the 4PL existed when I was shopping, that's what I would have bought.

I know that -- by the specs -- the 4PKS-R is faster than the 4PL. I don't know how the speed of the 4PL compares to the 4PK. I know that I can feel the speed difference between low-end radios and my 4PK, but I doubt an upgrade from the 4PL to the 4PKS-R would be noticeable for most, in most situations.

I'd stick with the 4PL.