Yesterday, in celebration of SEMA, we asked you for the worst auto aftermarket add-on. Today, we'll flip it around and ask you what's the best.

Simple. In our mind, nothing beats a bolt-on Roots-type supercharger. Just look at the efficiency map above if you're even for a moment thinking anything else beats it at making your car better.

You have something better? Try us in the comments below.

(QOTD is your chance to answer the day's most pressing automotive questions and experience the opinions of the insightful insiders, practicing pundits and gleeful gearheads that make up the Jalopnik commentariat. If you've got a suggestion for a good "Question Of The Day" send an email to tips at jalopnik dot com.)

Photo Credit: Wikipedia