throttling exhaust pipe

[ioni]

you said ke and stupid strozzarlo...su this are not entirely agree..

Got it !
Anyway, it takes the right section or reducing it too much gas to increase speed? but up to a certain point, after that they are not able pi? to drain properly, creating a "wall" in addition tot laps.
The study of an exhaust if you want it to do WELL ? a serious and very difficult, in all engines with performance medium-high (I exclude the lawn mower and then...)
Reduce the section, or to enlarge it without any other changes can? lead to benefits in certain regimes and losses in others, it is a "covered short".
Of course, there are sometimes the margins of the project on which to play but ? to assess on a case-by-case basis.
In principle, then I advise you NOT to touch the exhaust line if you do not know what you are doing.
Typically I could also on the diesel you try to have more? power higher revs (torque at low usually have too much) and we are looking for changes in this sense, then, de gustibus !

[angelolsp]

certainly useless to narrow it too much I agree ke you need to do right studying and testing to find the best condition and normal ke six one acts on the bottom loses on the top and always ccosi you can not have it all...for the top, you will make other changes, for example,

[savek]

but what kind of change

[mikyrace82]

consists in reducing the diameter of a section of the exhaust to create a turbulence...by doing so the fumes hitting this bottleneck, causing a sound pi? "racing" type turbo, high-pressure...If ? a light thing does not affect the performance but if you throttle too much you will lose performance, especially to the high, and rising the temperature of the engine....in a few words na tamarrata...