bonzotheripper

i was just wondering what would happen if you just port the irons but did nothing to the housings? on an s5 na and you were using the stock housings, would it do anything good or bad?

K-Tune

The stock intake ports on an N/A are already huge...

RotaryEvolution

you got it backwards...

n/a intake ports are already at maximum potential all around. the exhaust port on the other hand is a rather large restriction due to the exhaust diffuser, the exhaust port itself is also a little on the small side. but if you open up the exhaust you also create more noise.

the primaries could be opened up but then you lose bottom end response. secondaries are a wasted effort to port.

best all around compromise is replacing the n/a sleeves with turbo sleeves or modding them, i have a writeup on modding them for opening up exhaust flow. keep the rest of the engine as original as possible with the exception of a free flowing exhaust and you will notice a performance increase all around. bump timing up a few degrees and if you have an S4 about 10% fuel can be removed above 3k RPMs, S5 is already quite well in regard to fuel tune with the stock ECU.

bonzotheripper

thank you i will look into that write up , so just so i understand , there is no need to streetport an s5 na? with the exception of the exhaust ports?