Help, upgrade needed to beat my nephew in 20 mile dash
Over the last year, I've been racing my nephew on a weekly basis over 15-20 mile dashes. We ride mainly on flat paved greenways - mostly Silver Comet for those in Georgia. Well, the kid finally beat me a few weeks ago and now I just can't seem to keep up! However, I'm prepared to spend up to $1k to buy me another 6 months of competitive racing/trash talking with him - yeah pathetic, but nevertheless enjoyable.
I'm currently riding a Cannondale Supersix Rival with Ksyrium Elite wheels. Would any of the below listed bikes gain me some time over a flat 15- 20 mile course:
CAAD10 Rival or Ultegra: I briefly road a CAAD10 ultegra which seemed snappier, but was slightly too big for me.
Giant TCR advanced: How are the older TCR Advanced bikes - eg the original Advanced SL (I think 2009, 2010) compared to the more recent (2013, 2014) TCR advanced 2 models (105 equipped)?
Specialized Smartweld Allez or late 2000's Tarmac:
I've seen all these bikes (mostly older models) sell used for about $1k. How do the slightly older higher end models (eg the Giant Advanced SL or Tarmac SL circa 2009) compare to the the more recent lower to mid end models? Has technology improved so quickly that I should focus more on the latter? Any other budget "fast" bikes that I should consider - people seem to love the Argon 18's, but they're tough to find used and in my price range.