The reason for side exhausts is to keep the car straight (think of Pontiac's old slogan .... "Wider is better"). You would have to make sure that the bends are not too big, I hadn't thought of that part before. As for Xmods"man" (at 12 you say????) you can remotely ignite the rockets w/o buying expensive pre-mades. You simply hook up the igniter to an RX (receiver) board which is activated by the TX (transmitter) board through RF (radio frequency ... what the XMods and most other R/C's use). To Sawhit, I have no idea why you would have a servo hooked up to the system, a servo is a motor. All that needs to be done is hook up the igniter to some type of PCB/Board that would control when it fires. I'm thinking some type of Hi/Lo system by hooking it up to the headlight circuit maybe??
Basically, you would hook up the positive from the Headlights to the base of a NPN (Negative, Positive, Negative) transistor. For the NPN transistor, the wiring would (I think) be as follows:
Base (middle lead of NPN) would be hooked up-to the Positive for the headlights. Collector (first lead of NPN) would be hooked up DIRECTLY to the negative of the battery pack. Emitter (last lead of NPN) would be hooked up to one lead of igniters (make sure to wire igniters in parallel for "sure-fire").
For the other portion of the igniter PCB, you would use a PNP (Positive, Negative, Positive) transistor, the wiring would be just the opposite:
Base (middle lead of PNP) would be hooked up-to the Negative for the headlights. Collector (first lead of PNP) would be hooked up DIRECTLY to the positve end of the battery pack (opposite pack from before, you want as MUCH voltage going to the igniters as possible). Emitter (last lead of PNP) would be hooked up to the other leads of igniters (again making sure to wire igniters in parallel for "sure-fire").
All of this SHOULD ignite both igniters/rockets at the same time the very second that you pull the trigger for the car to move forward OR backward!! If you notice when you drive your XMod, the headlights go bright in both directions, but the taillights only go bright when you hit the brakes. BEFORE you do this, you will want to make sure to have the design checked out by someone that has plenty experience with electronics such as this.
WARNING!!! (have to have this) If you do not have experience with making the following electronics, be EXTREMELY careful or you will likely kill/maim yourself
The colors at the bottom are as standard ... red = positive, black = negative; the colors at the type end (the leads of transistors) are labeled in the JPG image.
Have fun
Here is the graphic for it: