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plog and 3" dp

04CompG

04CompG

New member
If I add a 3" dp with a high flow cat and front zzp plog to my car how will it effect the sound of the exhaust?

I've heard a few times that adding a 2.5" dp to a gtp is worthless. Why?

Thanks.
 


I have actually heard the opposite on the DP. I have heard that the 3" is worthless. I went with the 2.5" with my DP that I just ordered. I plan on getting a PLOG soon as well.
 
3" is a better choice. more flow. remember, you have a blower so you need a way to quickly let the exhaust gases out. there is no reason to have any backpressure on a roots blown system.
 
so what does the exhaust sound like with a 3" dp, hi flo cat and a zzp plog?

inside and outside sound. thanks.
 
04CompG said:
inside and outside sound. thanks.
Click to expand...

I just installed a Plog on a friend's 04 Imp SS which already had the DP. Sounded... the same. Kinda hard to tell any difference when he already had the resonator removed and runs dual Magnaflow mufflers.

When I put a 2.5" DP on my L36, I noticed it brought out more details of the exhaust note, but it wasn't louder. Just sounded like a speaker that had better frequency response. :)
 
Get the 3" DP, you will not loose low end power, you'll gain it if anything! (I'm talking from experience too, my car never lost low end). 2.5 probably won't be a restriction but why buy that when you can have a 3"? As for getting PEMS or a Plog, well I think both are a waste of money IMO and I wouldn't go that route at all.

If I were you, do it right and do it in one shot... Buy either Pacesetter or S&S headers (TOGs if you want to spend the $$$) and take care of your exhaust problems in one shot! You'll loose the whole ****ty restrictive manifold setup and get a nice downpipe too. And your not spended much more money doing this than getting a DP and a Plog. I don't care if your building a 14 sec car or a 12 sec SC car, Plogs and PEMs are a waste, leave them for the turbo guys who need them.

All you're accomplishing on an SC car is a nice DP and one decent flowing manifold, why?And no, you will not loose low end with headers. Just buy the headers, install them, and thank me for steering you in the right direction when complete. Its as simple as that. Good Luck...
 


Bio248 said:
3" is a better choice. more flow. remember, you have a blower so you need a way to quickly let the exhaust gases out. there is no reason to have any backpressure on a roots blown system.
Click to expand...


sorry i have to dissagree ...so your saying that a with a 3'' dp you total exhaust system will flow better then having a 2.5'' (the same size as the rest of the exhaust)? please explain. I had the 2.5'' off road with stock everything else...the exhaust notes changed a little bit but mostly at lower rpm's
 
the downpipe is acting as a collector for your manifolds. better collector means better flow.

by the time it gets downstream enough, it doesnt even need the 2.5" that most poeple have from the lack of expansion from the heat it no longer has.

hike skool fisiks, yo.
 
ok...I was more less talking about back pressure here. you said there would be less back pressure going with a 3'' reduced to a 2.5'' than just haveing a straight 2.5''. I dont see how thats possible. And with less back pressure on a roots style setup you would have less boost correct? keeping the same size pulley of corse. shoot the stock is close to a 3'' anyway besides where the the flange in welded to the stocker at...and it's only 10 bucks more....Im not trying to argue or be right...but rather to learn something in the process.



I could see what you are saying about it acting as a collector.But the back pressure would be greater at the reduced point instead of being greater at the manifold to downpipe point....wich at full throttle (or long enough to build equal pressure from the reduced 2.5'' point foward) the pressure would eventually be equal wether there is a 2.5'' or 3''....am i making sense?
 


Bio248 said:
the downpipe is acting as a collector for your manifolds. better collector means better flow.
Click to expand...

better flow out of the manifolds yes. but as soon as the pressure is equalized than the flow becaomes the same as it was before. I dont see how the exhaust can cool down over a 2 1/2 foot piece of pipe that much to matter either



Just saw a pic of your car in the tint post and man does it look good.
 
ok I know this is more or less history, BUT! with the 3" dp I personally would not even think about reducing me exhaust tubing, at least not untill after a split into duals. but that is just me. I mean why risk losing hp/tq for 2.5 to 3 ft of tubing. it might cost you an extra 10-15 bucks at the most. not worth it in my book. also if I'm mistaken or misled.....show me.
 
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