Originally Posted by LarThaL
I agree that catless/tune will give 25-30 whp. That is not 55hp. However, how much will a 25-30hp gain on top of 414hp make in your actual performance?
Lets look at this.
Firstly, even a stock M3 is traction limited in its low speed performance. Even if your car has 1000hp, it won't get off the line any faster. The first place to spend your money for actual increased performance is to increase the traction of the car so you can get the existing power to the ground better. So, you already need to invest in bigger wheels and wider tires.
Okay...so you argue that you are not into the whole drag strip thing, and that this is a "track car". OK, so in that case, let's see actual track times of otherwise equal cars with the only difference being basic NA mods. ( I say basic, because you are already talking about $4-5k for a good full exhaust and tune...about half the cost of a supercharger) I am willing to bet that all other things being equal, a car with just 25 more hp won't get around a track any faster in a statistically consistent manner. Your extra 25hp may get you a car length or two for all those times you get to an abandoned airstrip and can run your straight up to 150mph.
I reassert my point. By all means, do the NA mods, but do them for the change in subjective feel. Don't look for any meaningful actual performance gain.
And I am not in the least discounting the whole subjective feel thing. In the end, the joy of driving comes from a variety of sensory inputs and speed capability is only one of those.
Just don't kid yourself about what you are actually accomplishing. Believe me, I have done it all in 30 years of playing with cars....carburators, intakes, headers, exhausts, superchargers, turbochargers, standard and custom flashes, bigger and better this and that, etc. etc, etc. If you want clear cut power that you can really feel and use, get a supercharger, do the proper associated mods and be done with it.
Agree with everything you said.
40hp is a significant. BUT!, it will take a good driver and proper instruments to actually see the difference 40hp brings, at least, if you are road racing. But, a 40hp increase will definitely make the car faster for most of the driving M3 drivers do. Lane changes, merging and illegal road racing will see a benefit with a 40hp increase.