Mallet is based right down the street (literally, we're both on Bagley Rd in Berea, OH).
Being as close as they are, I have kept a couple of mental notes over the years between them and Lingenfelter. In MY OWN opinion,
1) Lingenfelter gives more bang for the buck.
2) Lingenfelter is MUCH more reliable (per numerous Car & Driver comparos)
3) I personally didn't find one of the Mallet Bros very personable. (One of my friend's worked for him at one time.) I don't recall if it was Chuck or Lance though, so this #3 is a questionable one at best. I've heard nothing but excellent things about Lingenfelter.
4) Lingenfelter usually seems to do whatever it is first, then Mallet follows. (383, 427, twin-turbos, Superchargers...)
5) Mallet appears to have won a recent shootout at the NCM where the supertuners gathered (according to their website.)
Again,
IMHO, I'd feel much more comfortable taking my money out to Lingenfelter in Decatur, IN rather than 2 miles down the road to Mallet. But that's just my opinion.
http://www.mallettcars.com
http://www.lingenfelter.com