If you are trying to modify flight time or increase thrust with your electric engine, your choice of battery pack can make a significant difference. The limiting factors you will run into are both the size of the location for the battery pack in the plane and what weight is suitable for the plane to carry.
An example of a common battery pack modifcation people make to a Hobby Lobby plane is changing the 1650 mH battery for a 3 cell 2200 mH pack. This gets the plane a bit more flight time but the jet ends up weighing a bit more after the modification. Although this isn’t necessarily a bad side effect for these jets, the added weight would definitely effect the jet in a climb. However, a slower climb might be a fair trade if you want to increase your dive speed and flight time.
If you are not sure how a new battery might affect your flight and would like some sound R/C advice from experts who want you to have an optimum experience, feel free to give Hobby Lobby a call. You are sure to receive excellent advice and customer service!