Aftermarket bolt ons vs OEM dispute

[tmontague]

After reading various car forums and what not over the past couple years when I became interested in modifying my car, I began to notice an argument consistently being made:

"If it actually proved to be beneficial wouldn't the manufacturer install in from the factory"


I thought I'd start a discussion on it to see what everyone's experience is.

The argument then maintains that the part in question therefore proves no benefit. I've seen this comment made for light weight crank pulleys, flywheels, air intakes, exhausts, oil grades etc. Generally they're made by people who haven't actually used them aftermarket parts or made these modifications themselves but seem to tow the same line as a reason not to.

I've always questioned that rhetoric and it never held much weight to me for a couple reasons:

1. Manufacturers have many variables to deal with that determine if something becomes installed from the factory. Performance is only one of these variables.

2. Emissions severely restrict the manufacturer from installing certain parts, or tuning an engine for more hp

3. Fuel mileage regulations (as well as the interest of the consumer demographic) limit these "performance" parts of modifications from factory

4. Noise limit is also another reason for certain factory builds

5. Driver comfort, many cars (especially the Yaris) do not come from the factory with a focus on performance. Meaning they are heavily on the comfort side of the spectrum which results in a hit on the performance side of things.

6. Engine reliability and longevity

These are not all of the factors but it is may of them. The argument; "if the factory decided not to install said part then it must not do much of anything" is circular reasoning at it's finest. Yes this argument may apply for certain engineering aspects of a car, but when it comes to aftermarket performance focused parts, many times it falls flat on its face.

Curious as to what others think, you now all know what i think