In regards to the blurble, I paid attention to this on Friday. My car only blurbles slightly when resuming throttle, not off throttle.
I believe I have a similar "burble" when getting back on the throttle slightly after coasting. I've read a few threads where the burble seems to be a "normal" occurrence. For me, the burble sound is very slight and doesn't seem to affect the performance of my Tubi or the car...Unless you can't stand it, I wouldn't worry about it too much. BUT that's only my opinionI talked to another member that had posted a thread a long time ago about this same issue on the other forum. Super nice guy. He insisted I call him. We talked for quite a while, and he told me he worked hard to solve the burble issue. He said the dealer told him it was the exhaust. They even loaned him a factory exhaust to try for a while. He did. He said the burble went away but he hated the sound. He went back to the Tubi exhaust and said he placed a large flat washer in the pipes just past CAT where the clamp is located. He said this really helped lot, and gave the car some back pressure to keep the burble down. It didn't affect performance because of the by pass system. I thought this was an interesting idea. It seems to be easy enough to try and is reversible.