Pipes??

I just got my second mustang, this time around I went for th 96 Cobra, it had some perfomance mods already compleated on it however I do have one question. It currently has Bullet mufflers that unfortunatly stop 1 to 1.5 feet from the read axle. Will it be more quiet (inside) if I extend those pipes all of the way to the rear of the car or would 90 degree down turns be better, and also if I were keep the current setup will I be creating a problem in my rear end with all of the extra heat?

Thanks