Dear Tom and Ray:

I have a 2003 4Runner V-6 that easily pulled my boat. So I bought a bigger boat. I would like to buy one of those super-heavy-duty Dodge Ram Crew Cabs with an enormous diesel engine to pull the new boat, but my wife won't let me trade in our house so I can afford it. So, I found ads for "performance modules" that claim an 18 percent increase in torque in my 4Runner, for about a grand. I'm hoping you'll tell me that one of these things really will work, and more importantly, that it will ruin my engine after only 2,000 miles, so I'll have an iron-clad excuse to buy a new, overpriced monster truck. -- Phillip

RAY: I think your plan will work, Phillip. I don't know if you can toast your '03 4Runner in only 2,000 miles, but it's worth a try.

TOM: All modern engines have something called an engine control unit, or ECU. It's basically a computer that keeps track of data from various sensors all over the engine, and then crunches the numbers and determines how much fuel to send into the cylinders and when the spark plugs should fire. The ECU's goal is to provide the best balance of power, economy and clean exhaust.

RAY: What most performance chips do is they replace the database that the ECU uses to calculate fuel and spark settings. For example, instead of telling the ECU that for a given set of conditions, send in X amount of fuel, the database on the performance chip tells it to send in 2X and advance the timing so that the spark fires earlier. That's how it creates more performance.

TOM: But the guys who make performance chips aren't concerned about things like reliability, longevity, fuel economy or emissions.

RAY: Oh, and those chips automatically void your warranty, too.

TOM: So, if your goal is to wear out the engine in your 4Runner, and do some damage to the environment in the process, I think this is an excellent plan, Phillip. Bon voyage!