Are there any exhaust mods that add no noise or even quieter? Of course add power
too.....


Mark
2003 coupe 6MT

Not that I know of. High flow cats or a good Y pipe will add some power with very little additional noise--most passengers will barely notice it, but as a daily driver of the car, you will notice a very slight increase in noise at WOT and a little bit more power.

interesting to hear people saying the "spacer" is noticeable.

Ive heard so many other people in the past talk bad about throttle body spacers as being nothing but a paper weight.

I dont understand what the "spacer" is supposed to do, its not increasing air flow, whats it doing???

Maybe this isnt the same part that Im thinking, anyone got any other info on this plenum spacer thing?


Anyway, I think the best way to test mods is at the drag strip, sure getting identical launches wont happen but averaging runs and big enough improvements will show.

I agree. As long as you compensate for atmospheric conditions, positive or negative results from mods should be clearly visible.

GfortheCPE,
This certaintly isn't a throttle body spacer. It's plenum/manifold spacer and it actually does increase air flow.

The reason is because the stock plenum has what bascially amounts to a design flaw. The plenum covers the 6 intake runners but because it has such a sharp slope the last two intake runners are only ~1/8" away from the top of the plenum cover. That's not much room to breath.

By putting a spacer in you allow the first two intake runners to flow easier. Hence the power gains.

Tony

GfortheCPE: I have no idea what the throttle body spacer is, but if it is what it sounds like - it would be worthless.

The motordyne spacer being discussed is a Plenum spacer.
That is to say the bolts holding the upper plen half to the lower are removed, the spacer is inserted, and the upper half bolted back on.

In effect it turns a stock plenum into something like a Crawfor or Kinetix replacement upper plenum.

It is useful as a mod, for the same reason the replacements are... and that is that
if you look at the stock plenum, it slopes dramatically from the backside (near the throttle body and firewall) toward the front... done apparently because of fit in the Z, and maybe other models that share the engine.

The dramatic slope reduces proper air supply to the cylinders near the front of the engine.

The performace change is very noticable, the advantage of the spacer vs say the crawford is that if you go with the 1/4" or 3/8" you can still fit the stock engine cover

If you go with a 1/2" then you can't put the cover back (like say the crawford hich doesn't allow the colver)

The other advantage is cost - a spacer is maybe a couple hundred vs 4 or 5 hundred for say the crawford.

Thanks for the your inputs on the following mods, I will definitely consider getting the 3/8" spacers.

oh gotcha

yeh not at all the same thing as a throttle body spacer that I was thinking of.

If you have a sedan, I'd get the 1/2". It fits just fine w/cover and no problems.