^^^

I guess it just comes down to personal preference; I much prefer an engine that drops revs quickly when I close the throttle - to me, hanging RPMs during closed throttle is design flaw.

I learned to throttle blip on downshifts back when I was roadracing motorcycles (some call that rev matching), and have been doing it in manual shift cars for over 15 years as well (slow and fast shifts - an ingrained habit for me now) - that technique works better with snappy, closed throttle response.

I didn't notice any difference in turbo spool time on up-shifts when I removed the vacuum limiter - maybe that would show on a dyno, or some sort of precision timing test on the track, but not with regard to how I drive.

I thought flat footed shifting was a version of a race-style speed shifter setup; no need to lift throttle, or even use the clutch with a sequential gearbox, on up-shifts as the ECU, or piggyback electronic controller, cuts ignition momentarily. Those are awesome on the track.


BUTT, the awful, 3LDZ turbocharger, which thankfully I don't use, needs all the help it can get, so maybe the vacuum limiter is a plus when running one of those?

Well that's what I'm confused about, why is that behavior better?

Flat footed shifting is for upshifting and is essentially a rev limiter that can tell when the clutch is in, so it limits your RPM to say 4,000. So you keep your left foot flat on the floor, put in the clutch, change gear, and the RPMs are at 4,000 not through the roof when you let it out in the next highest gear. Supposedly helps reduce turbo lag, though I've no first hand experience. I can't imagine how removing the limiter would make any difference accelerating in a gear, but I can see how dropping the RPMS fast between gears on upshift would be detrimental.

Heel and toe blipping works fine for rev matching on the downshift, but again if the RPMs are dropping slower, there's less need for it, although I need it to.

Guess it all comes down to what I tell my clients all the time, before you ask for something better, "define better". :D

The deceleration valve vacuum limiter is like not taking your foot off the gas all the way when taking your foot off the gas all the way...
..while the driver is having at it but of course.

They say it reduces nitrogen dioxide exhaust emissions out the exhaust pipe when decelerating because of that too.

Deceleration valve sucks and has to go immediately in my opinion too.
I sold the stoopid golden saucer valve years ago.
To each their own I guess.