i've asked questions in the past about noise coming from the DR or the pulleys or drivetrain but really havent come to a conclusion in fixing it. the noise is definitely louder than it should be. i visited bike stores only hearing that its normal. well before i changed my chain it wasnt as loud or loud at all until it started 'stretch" ...the new chain was put on according to the bicycletutor...wrapping chain around largest in back and largest in front (not going through derailleur pulleys) and adding 2 links for slack (1") ...my point is i thought it would be a problem if i found out my original chain was 2 links longer than the one i put on... i think this has to do with more tension on everything causing more noise to be on the pulleys. is this correct thinking or it has nothing to do with this?

thank you!

This subject was just covered in great detail yesterday in mechanics forum. The big/big method suggests the shortest possible chain. There is nothing wrong with that unless you want to change the cassette to one with a larger cog at some point. The little/little method will suggest the chain length that is the longest possible and it will work with any cassette within the RD's wrap capacity. If you have a setup with the largest possible wrap, than both methods should suggest the same chain length.

https://www.bikeforums.net/bicycle-mechanics/590356-chain-suggestions-w-length.html

I always use the little/little method with a RD that has the proper wrap capacity. Then I can use any cassette I want and not have to worry about changing the chain length.

It's quite likely that your chain was previously set the the longest useable length and now it's set to the shortest. Either will work, but the shorter one will certainly not be quieter.

Noise from the RD, cassette and chain can come from all sorts of problems including RD hanger misalignment that requires a special tool to check. It could also be something as simple as improper shift cable tension, a worn chain or using a dry chain lube.

i just figured out why it was so loud, while riding on my trainer. i have a triple crank. im using the middle. but when i shift up more (larger cogs) it gets louder. but when i shift the smallest crank and shift down towards smaller cogs, the noise is gone. i didnt shift to either extremes and the noise was gone. so i was wondering why it would be louder with a larger crank than small? is it because there is much more tension than the small? so my chain could be too short?

You don't know how to setup a RD. Chain length is not the issue, if you followed the info provided. It's not rocket science.

RD is setup correctly according to 4 different LB stores i went, thanks.