[Alan Roehrich]

What your combination requires will determine whether or not you see a gain. If you have a set of 4 into 1 headers that are the correct primary diameter and length, and your previous collector was the correct size and length, you may not gain much at all, and you may need to do some tuning to gain anything at all. If your headers are not the right size and/or length, then a good merge collector may offer a decent gain. But it still may require some tuning before you realize a gain.