stp357

I finally got my CAI installed, and it changed the sound of my exhaust!!! I have stock NPP which I leave open all the time on my 10 GS and I wasn't expecting this. It cut way down on the popping and gurgling on deceleration. I liked the popping and gurgling. And it quieted the exhaust while accelerating too. Is this normal? I had been contemplating an aftermarket exhaust, I guess this will speed up that decision.

SilverScorp

I have the Vararam SC2 on my 2010 GS with NPP and it sounds pretty much the same as before..maybe a tad bit louder. But it still gurgle/pops on deceleration.

Boomer111

I have never heard this complaint before.

I had the Vararam with headers and Corsa Sports and it had no influence with the exhaust sound. There was more intake sound though.

I eventually replaced the CAI due to regulations and the surging I was experiencing under light steady throttle.

If the car was tuned maybe the turner changed some programming limiting the decel.

I am not a tuner but I know from experience that it can be worked with a little.

not08crmanymore

Never heard of this before either.If you want a very aggressive sound back there with the NPP open or closed,install a set of headers and it will make the NPP a perfect sounding exhaust,and that from someone who is not at all convinced that NPP by itself sounds good.!Had the VARARAM,HEADERS and NPP on my last 08 and it was phenomenal!

glenB

Placebo effect

stp357

The car hasn't been tuned. And there is no placebo effect either. My wife noticed the different sound immediately upon my return from the installation, and she is definitely not a car person.

HOXXOH

If you install headers and remove the FRC's and the IM skull cap, you'll never hear the exhaust at WOT anyway. The screaming of the engine and sucking in air will drown out everything else. It's a much better sound than gurgling when slowing down.

Boomer111

Not sure what is going on but it does not represent itself has being the norm.

There will be an increase sound with the Vararam but your question is concerned with the NNP sound.

Maybe your getting more air making the fuel leaner and this might lead to less popping of gases. (understand that I haven't a clue and am just talking out my ***)

My tuner once tried to limit the popping on decel by adjusting, what I thought was a fuel table. It did have limited success on the popping and I don not remember it changing the general sound under acceleration.

stp357

Make sense to me until someone with more technical expertise will chime in and change my mind. Either way, there is a difference. I will say this, my Vette runs like a scalded dog with it.

raspyc6

any other conclusion is just silly

stp357

Thanks for that well thought out response!

Knob Jockey

I doubt this is the answer, but after you install a VaraRam without a tune, you have drive the car long enough for the ECM to adjust to the increased airflow.

HOXXOH

That's most definitely a placebo justification for the expenditure, since a .3 second 1/4 mile differential is not in the calibration range for butt dynos.

wera32

Sounds to me like the NPP is closed like your mtw isn't working.

Boomer111

Agreed it doesn't make any sense correlation wise.

gsflyer2011

Exactly the same thing happened to me 3 years ago when I replaced my intake filter (only) with K&N (11 GS with NPP, also run open all the time), I, like you posted it here here and I, like you I got ridiculed. I guess, for some people, what they have never heard (or don't know) cannot possibly exist therefore is or must be a figment of your imagination.

I put it on and off few separate times just to make sure I was not imagining it, even drove for a whole week thinking that the computer would adjust and compensate for it. It did not. My car sounded so sedate that I took it off, put back the original filter and sold the K&N here on the forum. My GS runs and sounds far better with the stock set up (over K&N)

raspyc6

I am sorry if a succinct and parsimonious response was not warm enough for all the fellas here. Not trying to be a schmuck but just wanna sorta deal in reality. Look, I can see how one might feel throttle response is a little different perhaps but to say the entire nature of the car changed with a CAI seems far fetched.

stp357

Who said that?

Twowheelin_wildman

My 2011 GS has the SC2 installed with a Diablo 93 octane tune and it changed the sound as well but for the better with a deeper sound ( im sure from the increase of air coming in) but popping never decreased. The whole set up did change the way the car runs for the better.. alot! Ive been very pleased.

dennis50nj

you should get one and see how it really does work, I picked up 5 mph and 5/10s in the 1/4 documented with before and after DA within 10 ft