Originally Posted by
Delmarva
You have the gearing to go very fast right now. However most of us with less than perfect legs can only take advantage of that gearing on momentarily thrilling downhill rides. As others have mentioned if you want to improve speed on the flats and hills the engine has to get better.
You have a wide range 8 speed in the rear and probably a triple in the front. The only change you might consider would be to tighten up the rear gearing some. And I would not spend the $40.00 or so on a cassette until putting some miles on the bike. You have plenty of gears right now. It's just a matter of learning to use them.
I believe OP has a road compact double. He may need those low gears to get up hills, especially if he is new to cycling. My personal beef with the bike manufacturers is pairing a 50 tooth chainring with an 11 - 32. The gearing is just too tall for a multi purpose bike. This isn't such a big deal when the cassette is paired with a triple, since most folks will use the 38 or 39 tooth middle ring most of the time anyway, but with a double, many, if not most people aren't using the 2 biggest gear combinations 99% of the time.