3 questions...

[DavidT]

1. I recently had my stock y pipe "modified" wink . My sho is sounding like a mad bumble bee (kinda like a "honda ricer". I am pretty sure most of the noise is coming from somewhere in the y pipe (closer to the engine) It is either a gasket or where it was welded. Could this be bad from a performance perspective? It doesnt really feel like it is running worse, just louder from directly under mt feet
2. Can someone explain the backpressure concept? Is it meaning that the exhaust NEEDS some kind of restriction in it to optimize performance? I wish I had a better understanding...
3. I am going to try to recharge my ac with freon. One valve is in the back (near the windshield) and the other is in front (near the battery). Both valves are not the same size. Is the one near the battery the one I want to connect the freon to, to recharge?
Thanks for any advice. thumbs_u

 

[SHOZ123]

Backpressure is pressure inside the exhaust manifold created by the restiction of the exhaust system. If there is no backpressure then unburnt gas before ignition will be drawn out of the cylinder due to the overlap of the intake and exhaust valves.

On my V8 I ran for a day with the exhaust sytem disconnected from the Y pipe. I thought I was driving a Vulcan.

 

[dkal]

In response to your question 3, the valve near the windshield is the one you want to use to add refrigerant.
Which is the suction side of the AC system, or the low pressure side. This is refrigerant is the larger diameter of the two.
The other valve is the high side which is the discharge side coming from the compressor

Dkal