Hi guys whats the advantages off port polishing?does it make the fuel flow better with less friction?

Bad for inlets ports. Google is your friend

Actually, it is a proven fact that polishing ports will slow port velocity.
Porting a head consists of cleaning the runners up to remove obstructions (small and large bumps) and casting imperfections. But, if you speak to any professional they will tell you that they leave the outer walls somewhat rough. The reason for this is to create turbulence in the port runner, this does two things 1) it creates turbulence that helps to mix fuel and air better, and 2) the turbulence helps to increase air flow velocity. Hope this helps.

What rgrinder has said is what I have been told by engine builders as well

This is not bad as a rule of thumb but there are always exceptions. I find it hard to believe that flow could be laminar by the time it gets to the port or even that the boundary layer would be laminar. Usually smoother is better, sometimes roughness can re-energise the boundary layer and delay separation improving bulk fluid flow. Think golf balls.

What I do believe is that on very smooth/ mirrored surfaces fuel does not adhere and then re-vaporise as well as it does to a rough surface. Smooth surfaces limit heat transfer. If the fuel is well mixed before hitting the ports, polish to your hearts content. Over all I think it's a waste of time going from smoothed to polished, it'll end up covered in carbon eventually anyway. At least I've never seen one from service come out clean.

lamb_daiquiri is on the money. There's some debate as to whether it might help on the exhaust port (the shiny surface might reflect a little bit of heat, or at least there's less surface area in the port itself if the surfaces are smooth, so less heat conducted away and more heat energy in the exhuast, slight gain in flow.

Having said that, I'd be pretty surprised if the gain was enough to even worry about on the exhaust side.

On the intake side, leave it rough. And if you are running e85 or methanol, both of which have more cooling effect (so more likely to condense on port walls) and also there's more of the fuel due to their stoich a/f mixture being so much richer than regular petrol - anyhoo, if you are running either of those fuels, it'd actually be cause to consider an even rougher finish for them. There's a head porter/engine guru in Adelaide with a bunch of speedway wins/result to his name (and a bunch of circuit racers too) and he's mentioned in the past on peformance forums that he leaves the ports rougher still for any engine running on methanol.

The thing that one needs to remember is that in an "ideal" situation with constant air flow polished ports would work very well. However, internal combustion engines don't run in ideal conditions. First off the rpm changes as speed increases or decreases which changes air flow speed inside the port. And second and more importantly air flow inside the ports and manifold runners stops and starts with the opening and closing of the valves. Ever noticed how the exhaust pulses at an idle? The same thing is happening to the intake side of things also. Headers (extracters) are used to help smooth out those pulses and create a scavenge effect on the exhaust side, gasses passing by another pipe will help to suck the exhaust out. On the intake side, the manifold runners do kind of the same thing except that the only place they meet is the beginning, the air/fuel mix is drawn down the runner while the valve is open, when the valve is closed the part furthest from the intake valve keeps moving, causing what can be best described as a ram effect, loading the runner with more of an air/fuel mixture.
Anyway, to make a long explanation shorter, with all the starting and stopping of the air/fuel mixture, the rough ports help to keep things stirred up so that the atomized fuel in the mix doesn't condense and cause fuel puddleing in the intake system.