Andre from Livermore
A redundant battery pack is a very good Idea, whether for balance or peace of mind. You will need a pack of equal size to your main pack and a separate switch/charge jack for this pack. Then simply plug it in to an unused servo port on your receiver then you will have to charge each pack individually.
As for as the exhaust for the 180, I think you can buy aftermarket header pipes to lenghten your standard ex.