It's possibly an engine mount that's causing it rather than anything suspension related.
I'm not sure how you would effectively nail down the exact culprit, but uprating engine mounts is a worthwhile job in itself when you're tuned, so maybe it's worth the investment knowing there's a good chance you'll cure it.
Sometimes it's a case of replacing mounts and bushes starting at the cheapest, and sometimes that gives you an excuse to upgrade.
Best of luck.