Piston Slap: The Fallacy of Aftermarket Performance?

(animation courtesy: store.034motorsport.com)
Evan writes:
Hi Sajeev!
How do people get your name wrong when it is in your email address? But that wasn’t why I was calling. My question: are aftermarket parts for brand spanking new cars sensible?
For instance, I’m picking up an Audi SQ5 and there are these ‘x-brace’ things and mount inserts. Why would Audi not have engineered it well enough in the first place? Money savings? They didn’t think whatever attribute x-braces add was ‘for’ the SQ5 demographic?
Or are companies selling mount inserts and eXtra bracing to people with $60k sport-crossoverUVs selling snake oil?
Thanks for the insight!
Sajeev answers:
You can’t make generalizations — except about the horrible people calling me Sanjeev even though my name’s been plastered all over TTAC since March 2006…but I digress.
Vehicles are designed to a certain expectation of performance, ride quality, cost constraints, and acceptance to a wide variety of consumer preferences. Aftermarket performance modifications can do better than factory stuff.
But some are worse than other aftermarket alternatives, especially against those of a creative and grassroots racer nature. Sadly, many (either by themselves or in a package) only make a difference to the owner’s perception of vehicle performance and some parts are worse than what came from the factory (i.e. oversized throttle bodies on a naturally-aspirated motor). Take it from the guy that loves tweaking RWD Fords: every scenario above is true.
It’s like walking through a metaphorical minefield: keen research, trusted advisers with years of hands-on experience, and hours of internet forum digging are mandatory to sort fact from fiction.
So, shut up and tell us, what’s the scoop on these SQ5 bits? Well, I’ve never driven said vehicle…
However, I rather like those billet aluminum bushing inserts, even though billet and anodized finishes are often overpriced flash. Yes, many forms of motorsport require such fancypants materials, but that doesn’t apply to the SQ5. Flash doesn’t sell me; tangible improvements in performance does. To wit, these babies likely improve performance out of the hole, especially with an aftermarket computer tune bumping up performance, reducing torque management and perking up throttle response.
Yet I wonder if there’s a universal fit, solid (rubber or invasive polyurethane) bushing you can buy from a catalog (or from another VAG product) — which might be like, waaay cheaper, son.
And since a new Audi is far from the flexi-flyer chassis of my beloved Fox Ford products, I question the value of any chassis improvement on a higher dollar luxury car, much less a billet aluminum one. Does it stiffen the chassis and improve feel enough to matter? Maybe it helps NVH control. Perhaps handling is more confident with other modifications. Odds are, though, it won’t make the SQ5 any quicker on a track.
Consider, if you will, improving the factory part: adding metal (perhaps triangular sheetmetal between the weak points?) welded it up by someone familiar with roll cages. Perhaps that aftermarket part is a good template. That’s more labor and it won’t be billet aluminum pretty…but, right or wrong, it’s the other side of this coin.
Don’t forget one other important fact: modifications are worth pennies on the dollar in the vehicle resale department. Many will lower the value as stock vehicles are preferred at trade-in time. The SQ5’s bits add curb appeal for buyers motivated to get on their hands and knees to see them, which amounts to precisely nobody in the used car market.
Don’t get me wrong, I love modifying cars with cool aftermarket bits, but it boils down to two words: buyer beware

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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