Best Free C4 Corvette Performance Mods


Looking for some cheap (free) performance mods for your C4 Corvette?

There are four weight-reducing modifications that can be done to a Corvette C4, all of which are free or pretty cheap. Reducing weight means it requires less power to move the car, making it faster. These modifications include removing the Frisbee, eliminating the muffler, air smog pump eliminator, spare tire removal and improving the air flow.

Below is a description of the top free C4 Corvette mods/upgrades. There are some pluses and minuses to doing these changes listed below.

Removing the Frisbee

What is the Frisbee, and what is the potential HP gain from removing it?

The Frisbee is an optional 10-pound piece installed to dampen out vibrations caused by the AC. While the HP gain claim isn’t proven, removing it makes the car 10 pounds lighter.

When I purchased my 1985 C4 the frisbee had already been eliminated. This is a pretty popular mod and I suspect it has been removed before you purchased your C4 Corvette. But in case it’s not, I wanted to mention it here.

Eliminating the muffler

What is the purpose of the muffler, and what happens when it is removed?

The muffler’s purpose is to reduce the engine’s sound, but when removed, the car emits powerful and intimidating sound waves. Removing the muffler also makes the car 25 pounds lighter.

When I purchased my C4 it had the mufflers on the car, and they looked like they could be the originals. The were in pretty bad shape and would need to be replaced in the pretty near future. My C4 also sounded pretty quiet. I decided to go with the muffler deletes which effectively did two things for me. It reduced the weight and gave the Corvette a better exhaust sound.

This one is not totally free if you purchase eliminators. But there are several to choose from that should work with most any budget.

i highly recommend this if the rest of the exhaust is stock. This can change if you decide to do more changes like going with straight exhaust or something like that. In that case you will probably want mufflers, otherwise your C4 will be super loud. But it’s your car, do what you like.

Air smog pump eliminator

What is an air smog pump eliminator, and why do many C4 owners remove it?

An air smog pump eliminator is a modification that removes the air/smog pump placed in the car to reduce tailpipe emissions. Since it doesn’t add any horsepower, many C4 owners take it out.

My air smog pump is still on my C4. I haven’t done this yet so I can’t speak to it’s benefits. Might be something I do in the future.

Spare tire removal

How much weight can be removed by removing the spare tire and tire carrier, and what is the potential HP gain from doing so?

Removing the spare tire and tire carrier can remove 40-50 pounds, which can increase the car’s horsepower.

One important note here, the spare tire was part of the rear end safety features on the C4 Corvette to help in a rear end collision. If it’s removed you are in essence impairing that safety feature. We never think we’ll be in a wreck until we are. Just something to understand when removing this.

Also, if your C4 is like mine the spare is the original and super old. it’s not really going to work if you get a flat. There are some options out there for a spare tire replacement for your spare tire rim, but they are usually hard to come by.

I personally have not removed mine. I figure I’d rather keep this safety feature in place. The 40 or so pound weight loss would be nice but I’m not normally out racing people on the streets and you shouldn’t either.

Upgrading the air filter

Why do stock air filters restrict the amount of air they let in, and what is their focus?

Stock air filters are designed with longevity and quietness in mind, sacrificing power in the process. They are filtration-focused and, as a result, restrict the amount of air they let in. There are several out there to choose from including K&N filters.

Once again, an upgrade that does cost a little bit if money but with several to choose from there is something for every budget.


There you have it. Some very inexpensive ways to improve the performance on your C4 Corvette. Just be aware of the implications of doing some of these changes like removing the spare tire.

These cars are very capable performers and these changes can help improve that ever so slightly. Coming soon, upgrades that cost a little more.

Question or comments on this post? Please leave a message below.

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