Both the 2008 and 2009 Giant Cypress DX have a 28/38/48 crankset and a 11-30 cassette. So the question should be "did I ever use the 28-30 gear yet?" and a 11-28 cassette would not be any change at the high end as the Cypress DX already has an 11-30 cassette. Perhaps a 30/40/50 or 30/42/52 175mm crankset? The Giant Rapid 3 has a 30/42/52 crankset and 11-28 cassette.

To be specific perhaps these modifications will make your ride faster:

Road bike saddle. Too many good choices to mention, your preference prevails.

Rigid seat post. A good aluminum one wouldn't necessarily break the bank.

Road bike stem and flat handle bars. The NVO Components ATS stem with a Ritchey Comp flat handlebar (5D bend x 580mm wide) are really nice. You should look into those and others like them.

Road tires. A good set of 700 x 28c tires with fairly robust puncture resistance would speed things up quite a bit.

Higher geared crankset. A 30/40/50 or 30/42/52 crankset with 175mm arms would give you more top end.