The EGR valve only works at part throttle on any engine, so any affect it would have on KR would only be during part throttle operation and it would have no impact on full throttle performance (or KR at WOT) at all.
That having been said, 3800 SC engines only have an 8.5:1 compression ratio and you should be running premium unleaded fuel at all times in one of these engines anyway (so you don't hurt it when giving it boost) - therefore there is virtually no risk of any KR or a hot running engine due to the EGR being eliminated - if you so choose to delete it from your 3800 SC engine.
Since it doesn't hurt performance, there's really no reason to remove it from your 3800 SC engine if it is already on there and in working condition. I've seen more guys introduce problems by deleing the EGR because of the leaks they create by not properly sealing the EGR system holes in the intake and exhaust. I've heard guys claim that having a working EGR valve coats everything in the intake (including the supercharger roots) with a black carbon residue after long-term use, but I've never seen any evidence to suggest this small amount of carbon buildup hurts performance one but. It is more of a cosmetic concern I believe. The truth of the matter is you will still get a carbon buildup inside the intake of any engine even if it has no EGR and no PCV system due to the fuel vapors condensing on the intake walls after you shut the engine off.
So my advice for anyone is if you already have a working EGR system on any engine you are using, there are going to be virtually no benefits to deleting it other than cleaning up the appearance of the engine. If you are building a Turbo setup with a different intake that would require you to go thru some pains of getting the EGR system to work, then it probably won't be worth your efforts to install it (due to the low compression ratios turbo engines generally run and the less benefits of having a working EGR would bring to this configuration).
The job of the EGR is to introduce inert combustion gasses into the cylinder to help cool combustion (reducing NOx emissions) during normal part throttle operation. On some applications, having a working EGR valve may result in a miniscule increase in fuel economy. Engines with low compression ratios, and even high compression engines with big overlap camshafts, will have little benefit of having a working EGR valve installed since normal part throttle combustion pressures (and temps) will be relatively low anyway.
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[This message has been edited by Darth Fiero (edited 02-20-2014).]