RE: make it faster?
Well here's a good upgrade for ya that I wish I would have tried when I was running the PB Hydro's. As mentioned the radio box needs a bit of weight shifting or removal, the PB Hydro's are very Tail Heavy.
Replace the 4-AA battery holder with a Lipo Battery and a UBEC.
The 6v 5 cell hump back NiMh pack that I use is just over 1\4lb at 121g. A 4.8v 4-AA cell NiMh pack is just Under 1\4lb at 108g, the Stock battery set up is about the same.
The 7.2v [link=http://www.headsuprc.com/servlet/the-1458/Lipo-Battery-7.4v-/Detail]800mah Lipo[/link] is a mear 1.5oz\43g, and the [link=http://www.headsuprc.com/servlet/the-1411/UBEC-3-Amp-/Detail]UBEC[/link] weighs only 9g. I just ordered the 800mah Lipo set up for my JAE12G Rigger, Depending on what run time I get from the 800mah, they have a 600mah that weighs 1.1oz\31g or even better a 400mah that's .9oz\26g and it's Dinky Dimensions: 1.4 x 0.75 x 0.75 inches. I think I'll be upgrading a few boats to Lipo's soon I know my little sport .18 hydro's will love to see that 1\4lb anchor go.
[link=http://www.headsuprc.com/servlet/the-1458/Lipo-Battery-7.4v-/Detail]800mah Lipo[/link]
[link=http://www.headsuprc.com/servlet/the-1411/UBEC-3-Amp-/Detail]UBEC[/link]