Mods that don't directly affect engine and transmission that make c63 faster?
 

Excluding those which make car lighter, i.e. carbon fiber hood and removing back seat.

I am thinking more along the lines of a big fin diffuser en lieu of the oem diffuser or mode carbon's big trunk spoiler instead of the oem p31 spoiler. (Again, I am not referring to issues of lowered weight due to a carbon fiber diffuser vs the oem diffuser)

I realize that these are largely aesthetic, but is there any evidence that by affecting air flow, lift or drag, that these mods do make the car incrementally faster, say, in the 1/4 mile?

While I realize that these changes are unlikely to alter what happens on a dyno, could these changes make a difference of thousandths, hundredths or even tenths of a second on a track?

While it would be difficult to detect whether or not such minor changes to a car's exterior might affect 1/4 mile times, largely due to the lack of precision and reproducibility of human driving from one run to the other, I still wonder if anybody out there can answer this question based on academic knowledge.

Any engineers out there?

probably nurburgring and amg stickers should help, i noticed vast improvements on my jetta when i put neuspeeds stickers on it.

Aerodynamics assist with lift (not speed) or drag but that would only be nearing top speed where it could have any meaningful impact. Anything else is snake oil other than the stickers vdub mentioned which have actually been shown to improve driver ability and acceleration. Otherwise, if you want to go faster you need to change something that has something to do with going faster.

Didn't we already collectively determine you are allowed any go faster mods? :D

Only 1 vehicle I know had its hp increased from 276 to 330 with an M-Spec Nur badge. R34.Rated 276 factory but was 330. True story.

If 1/4 mile is your goal then suspension is a large component of 1/4 hook-up et's, BUT you would not want to drive the car on the street after optimizing the car for 1/4 hook-up.

1. Wgt Transfer.
2. Loading the rear tires on launch.
3. High stall convertor.

My Vorsteiner diffuser & big trunk spoiler are giving me at least 20HP.. I can feel it, trust me. LOL

OP, just enjoy your new mods... most exterior mods are purely cosmetic, sorry to say. I know it would make us all feel better to spend on mods & gain something out of it (performance).. but the reality is nope. LOL

Take a driving class, This will help you learn to drive soooooo much better.

Tires make a big difference getting it off the line!

If you track your car, as opposed to doing just drag strip runs, upgraded brakes (pads, rotors, lines, etc.) will definitely help improve lap times.

higher octane fuel

Driver mod

+1... best investment is in the driver :D

The absolute best modification you can do that will not void your warranty is reduction of drivetrain unsprung rotating mass. Lightweight replacement 2-piece brake rotors front and rear will save nearly 40 lbs and improve acceleration, braking, handling & ride quality. Also, getting lighter wheels with lighter tires can also massively transform your cars performance. Between both of those modifications you should be able to massively improve the performance & feel of your car and not a single one of those things will violate warranty as they are all considered "wear & tear" / cosmetic items. Ironically enough they are by far the MOST beneficial to your performance and would be the equivalent of 20x the reduction of a carbon fiber hood which doesn't do crap for performance relatively speaking.

Reduction of unsprung rotating mass is the holy grail of weight reduction & performance improvement, everything else is secondary ...

Ummmm..tounge in cheek right??:)

Best suitable mod in your circumstance is the road mod find a steep hill accelerate down it.. you will be faster then flat or iphill acceleration

AMG Driving Academy.

I always felt that a good clay and wax decreased air coefficent of friction across the paint...that surely is good for a few 1/10ths

Is it better to leave spare tire and jack for more rear weight? maybe add a sand bag or two

Speed Holes

+1

In a few steps:

Good sticky hi performance tires and light weight wheels will improve your performance without even opening the hood.

Next up AMG driving academy. great way to spend $1200 to learn the reaction of your car and other hi performance cars at limits. 9 hrs of driving - Zero liability.

Correct,

Also, don't forget on top of lightweight 2-piece brake rotors to also get high performance brake fluid (Castrol SRF is the best). Castrol SRF will eliminate most if not all brake fade due to its extremely high boliing point. F1 used to use Castrol SRF, that's how good it is.

None of these void warranty and are completely safe and will drastically improve your lap times around a track compared to a stock car (even if still at stock power rating).

Definitely get some lightweight wheels for it. We can get that part done! Just send us a note here and we'll hook you up.

^ This.

Only drive your car downhill.