What is a “Mail Order” tune and will it work for me?

For some, a mail order tune will work just fine but for anyone that has modded their vehicle I would recommend a custom tune on a “loaded” dyno. Mail order tunes quite often add a little timing, lean out the air fuel ratio at WOT and call it a day. Typical gains from a mail order tune are typically 15rwhp or so on an average fuel injected car and gains with a custom tune are usually in the 25rwhp range. (see my post on “Understanding Dyno Numbers”)