I am an English native speaker.
Both sentences have exactly the same meaning. In that sense both are correct.
What are the differences? Subtle.
The first is more colloquial or "natural". The "have" doesn't add any extra meaning for an English speaker and so would normally be dropped. At most you'd hear "...you've ever made".
At the risk of stereotyping, I'd say that American English tends more to these shorter, clearer constructions. British English generally favours the "correct" versions.
The second sentence is "more correct" and should be used in a formal context.
English is grammatically ambivalent enough that in most contexts (especially the one implied here) you could use the version that gives the best impact (the first one) and not get pedantic over grammar rules.
It probably also adds to the confusion that "made" is the shorter past tense and it doesn't change in the longer past tense ("to have made").
"I made the changes" versus "I've made the changes": the change in tense does not add a whole lot for most pragmatic circumstances.
With some other verbs (I sang vs. I have sung) you can see the difference immediately but with "to make" it's not obvious.
- About "ever": this implies some sort of limits to the time scope (c.f. the opposite, "never"!) so by definition you can use it only in the past or future tenses e.g. "The biggest mistake I [will] ever make".
As noted above, English tends to emphasise the pragmatics (conveying meaning) over grammar (finding constructions that always convey the same menaing), so the "will" in the above sentence is optional; this might confuse anyone who thinks that future tense always has to be signified explicitly.
