It won't. The dp will flow more but the stock car will compensate. The stock tune isn't asking for more so the car will probably just run more efficiently to get requested power.
Experience, I ran dp on stock tune for a yr, no issues to performance.
I also have run my Stage 2+ car in the stock tune mode and saw no adverse effects at all.
Just for some additional thoughts/info:
On other platforms, there has been plenty of experimentation with improving flow in the engine, which ultimately reduces knock/detonation, and allows room for more timing advance, boost, etc.. I used to do a lot of this experimentation and tuning on supercharged platforms. The same is true (though not always) that if you improve the flow characteristics and don't try and increase boost or timing, you can essentially run less octane and not cause detrimental effects (depending on how close the original octane rating is/was to causing detonation and timing reduction in the first place).
That being said, I am well aware that our vehicles (in my case the Mk6 Golf R) require a minimum of 91 octane fuel, in stock trim.. Holding that constant, if I add a free flow exhaust, intake, etc. and don't change anything else, there should be more headroom from detonation for the same octane fuel. I would then assume that dropping down an octane point (or 2? 3? etc.) would still allow the engine in stock form to perform well at stock timing table settings and boost levels without causing any issues. That in fact is what I am curious about, and wondering if someone has tried this, recording any engine timing, etc.
I certainly am not doing this to try and save a ton of $$ over the long run (as I would rarely ever operate it with lower octane fuel, since I consistently run 93 octane). However, am very interested to know if I decide to fill the car up with say 89 octane for a long trip across the midwest, how would it do??