why not just wrap the silencer and tail pipe in small internal 
diameter copper tubing, run the pipe through your existing ducts to 
the front, and hook it up to a junk yard a.c. cooler off a compact.  
fill it up with water, hook up a fan and you are set.  dont forget to 
add flex line where there is high vibration and a pressure release 
valve so it dosn't blow up.  As the water heats it will rise to the 
cooler and the cooled water will cycle back to the tail pipe.  No 
pump needed.
    This may only work in my warped world of theoretical jerry rigged 
physics. 
 you would love to see some of the things I have accomplished with 
duct tape.