My 305 '90 RS (common car among these forums) does not have a muffler, the exhaust manifold connects to the pipes running through the underside of the car attaches to the catalytic converter then out and ends near the middle of the car. a mechanic at my work told me that the absense of a muffler will result in a small loss of power, i dunno his reasoning behind it, but is this true?

 

the lack of back pressure could cause it to lack power on the bottom end but on the top end i could help you, but the lack of back pressure could ruin your vavles ,if you like the sound of straight piped just put on a cherry Bomb muffler it should have enough back pressure for your car.

 

If you still have a cat on it that will also give you back pressure.

 

sorry for being a noob, but what's top end and bottom end?

 

high and low rpm range

 

Back pressue is a myth, give me one reason how it could help you at all...

If I were you, I would get rid of the cat and put in a nice muffler.

 

Back pressure is not a myth. If you have ever changed from stock pipes to aftermarket free flowing pipes on a motorcycle you could easily feel the difference. Thats why manufacturs like Super Trap give you plates so you can tune them.

 

Well seriously, explain to me WHY it makes a difference. I cannot see why. If you can prove to me within a reasonable doubt, I wont have a problem admitting im wrong.

 

Don't get me wrong. I am not saying you need back pressure. In fact when you eliminate it then power is not being wasted. But things were designed with what back pressure that is present in mind. I use a motorcycle as an example because it is the easiest thing and will show a big difference in a simple change of slip ons. Just from changing the slip ons you could notice it feel like a slug in the lower rpm range but feel a boost in the upper. Thats why you would have to do a re-map of the computer or re-jet the carbs. Thats why Super Trap uses baffle plates. So you can tune your exhaust to your engine. Not for sound.I can not explain why backpressure is important because its not really. You just need to tune for the loss of it to gain the performance it gives from freeing it up.

 

from what i have heard inless your running a race motor you need back pressure,other wise your vavles will float causeing the vavles wear faster and could cause engine damage in the long run, just put a turbo muffler or a cherry bomb glass onpack on,they will give you a mean sounding car but will also give you the back pressure you need for a stock motor.