19's are better for go without a doubt. I would do 20's for show and cruising. But if you plan on doing some serious hard driving stick to 19's.

We are HRE's largest dealer, if you want HRE's look no further.

I have a set of HRE p47's 20" in gloss black brand new

I also have a set of HRE 790R's in 20" brushed/chrome

Here is a 997 Cab we just did yesterday on 20" HRE P43 Brushed Face/White Windows




some others.

 

There are several 20" wheels around that weigh significantly less than the 19 inch OE wheels that come on the car, so wheel weight need not be the issue.
Tire sidewall stiffness will cause a modest increase in ride stiffness. However, you almost never see a post on these forums from 20 inch guys complaining about ride comfort.
I suggest you buy what you find visually pleasing. If you are looking for track wheels, that's a whole different situation.

 

This is true, I have been over 165mph in a NOS powered 997TT with 20" wheels on it.. actually the car felt better planted on the 20's.... no complaints on ride or anything...

 

Thank you forgedwheeler, that was the kind of answer I was looking for. I dont track the car but drive it as if its on the track if you know what I mean

much appreciate the info, so you are basically saying that as far as performance (in terms of handling) the 19 or 20 inch will not make a difference. Is that true?

 

You know, handling as far as tire compliance the 19" will better at the track. But for daily real world driving and performance.. highway speed handling thw 20's will be great, better then oem due to the lighter unsprung weight and wider contact patch.

on a 997, 20's in the way I would go.

 

keep your stock 19's then switch to them when you decide to go to the track.