Lets Say I Got Tune For Cut Out Closed.....and I Drive With Cut Out Open,,,
Do They Alter The Air/fuel Ratio? Does It Loose Power?
Thanks!

 

Always tune with the cut-out open....Then when closed you might run a little rich, but you want performance to come when its opened, if not then why have it?

 

true that,,,,,,,,but i want my enigne to be last really really long without any problem...
if i run a little rich, isnt it gonna give u a problem later on.?

al dyno flash told me to tune with close if u drive most of the time with close....

 

and he said the map would be totally different.............including timing a/f ratio .etc....i guess

 

There is no reason AFR would change from changing something in the exhaust. The ECU is fully aware of the mass flow rate through the motor, and will adjust accordingly. The only change may come if you drop onto a lower load map with the cutout closed, which will lean out the AFR slightly, and increase timing slightly, but that the ECU's job In my case I use a tail pipe silencer that is very restrictive, and probably a more extreme example than using a cutout. I see absolutely no change whatsoever in the tuning, but I also run DSMlink so I am always on the highest load maps with or without it. But it proves the fact that the ECU is aware of the mass flow changes with and without it.

 

But Why People Tune It After They Change To 3''tbe?

 

Same thing, nothing should change. I Suppose you could get a little more aggressive with the tuning though, but I don't see that being worth the cost. Being able to tune yourself really is the way to go. Or perhaps this is an EVO thing. The DSM load maps only went to 2.1 grams/rev, which is pretty easy to hit. Then your AFR and timing become fixed targets at all times under WOT. The EVO maps go higher than what the stock turbo seems able to do, so perhaps this is the missing link. But I'm just thinking out loud at this point.

 

i really wanna get cut out,.,,,but the tuneing is the main problem for me!

any idea?

i want quite exhaust sound yet gives good power......so should i run the double (DUAL)stock pipes and muffler after the cat?
some racing cars have dual exhaust....thats what i want for my evo,,,,,,,,,

 

Air fuel might stay the same, but the reduction of back pressure will cause the turbo boost setting to rise which will cause a A/F to change...

 

bump