If you perjure yourself in voir dire you're in deep trouble. I can't remember the wording now, but as I recall I've always been asked something along the lines of whether I could deliver a verdict based solely on the law and the facts, and be impartial. Depending on how they word the question, it could mean a lot of trouble if you get into the jury room and start expounding on jury nullification.
I'd base my judgment solely on the law and the facts. Of course, my understanding of the law might not be the same as the judge's
Like I said, it won't really affect my vote, but I'll be more cautious about it, and pay VERY close attention to voir dire questi0ons and questionnaires.
If they can prove that when they asked you if you would uphold the law that you had no intention of doing so then yes, they can get you for perjury. Even if they can't prove you had premeditation to do so, there is an argument that can be made that since they asked you about the future, that you should never have said yes to the question since they told you in the question the scope of the trial. ie; They normally ask "Do you, juror x, believes that you would be unable to follow the law as I explain it to you, apply that law to the facts that you find in this case, and render the verdict required by the law as I explain it to you?" A lot of times they will follow that up with another question stating the nature of the crime, etc or weave that into the above question.
Whether or not it could be proved, and thus whether or not one might be exposed for doing what you suggest, deciding not to follow the Court's instructions on the law is a plain violation of the juror's oath.