When I rev my engine above say... 3,000 RPM and let off what I'm assuming is the aux. ports is chattering a bit and the engine does a "glug glug glug" kinda thing until it falls down to 900 or so RPM. I've heard other RX's do it plenty of times, but is this ideal? Is this sign of a "perfectly" healthy engine? Or can this be remedied down to a smooth rev drop sound and no chattering? Engine runs just fine. Just wondering if this is ideal...

I have a cone filter/air box and less restrictive aftermarket cat mated to a 2.5" Y pipe and MazdaSpeed canisters.

 

No, its supposed to be smooth all the way down.

 

i've been told that it's normal for the engine to "glug"on decel. and the chattering could be a timing issue. i say that because when i had my rebuild done it chattered loud on start-up and stop after it starts. came to find out my timing was waaaaay advanced and after retarding it a few degrees - it went away

 

its not bad. it just has a little glug glug on decel. the chattering is not bad either. just sounds like pop corn for a second coming from the aux ports?

 

nothing comes out of the aux ports. the aux ports opens after 3500 rpms to let more air in the engine. the popcorn sound could be just a lil backfire