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things that should never go on a grand prix

blowfishRus6 said:
haha nooo. it just took me so long to get to that point, im excited :D

3in dp man. gottaa get that air out. to bad you still dont have your p log either. tune doesent hurt either. that exhaust colder plugs, could maybe drop a few pulley's. hey gotta start somewhere right??
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Well im gonna have a lil more money than I thought, so im gonna go with a 2.5 dp, u-bend delete, Intense pcm & 104's. So hopefully that will help out alot.
 




blowfishRus6 said:
utt ohhh, maybe atleast a 3.5?? and why 2.5 dp??
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The reason for the 2.5 dp is to keep the velocity the same (well close to it). Plus youve got a 3in pipe full of exhaust gas trying to comeout of a 2 1/4 in pipe. With a 2.5 there isnt as much of a bottle neck. The 3.5 all depends on knock.
 
i got headers and a 3in dp bottle necking into the catback. its not hurting anything. a 2.5 is pretty much the same as a 3in tho so really i see no difference.

i wouldent be all scared of the 3.5 people run 3.4's with less. but yea always good to watch for knock.


sorry joe :/
 


Bio248 said:
there is no reason for anyone modding a grand prix to ever buy a 2.5" downpipe.
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Why is that? With a 3in dp you'll need to be pushing some serious power ( 3.2 and lower, turbo'd). With a mild setup all you'll do is choke the exhaust comming from the dp to the cat, and change the tone of the exhaust. A 2.5 dp will help to keep the exhaust flow @ a smoother flow rate and not so much as a bottle neck. This topic could go on till we are all blue in the face lol. I ran a 2.5 dp on my gtp and I saw no issues what so ever.
 
well agian, i have pacesetters with the largest primaries for our exhuast with a 3in dp. theres no issuies. plus its just gonna run strait into the resinatior anyways which is gonna slow the flow itself. i could see if you had strait pipes to out the back but its gotta go threw other things before it even gets out of the car. so a dp is not gonna be the only thing hendering flow. my opion, mine as well get that hot air out, away from the engine as far as possible and let the rest of the exhuast take care of that. wouldent wanna restrict hot air right at the engine.

but either way, its 1/2 an inch, i dont see it make much of a difference, its still a high flowing downpipe.
 
blowfishRus6 said:
well agian, i have pacesetters with the largest primaries for our exhuast with a 3in dp. theres no issuies. plus its just gonna run strait into the resinatior anyways which is gonna slow the flow itself. i could see if you had strait pipes to out the back but its gotta go threw other things before it even gets out of the car. so a dp is not gonna be the only thing hendering flow. my opion, mine as well get that hot air out, away from the engine as far as possible and let the rest of the exhuast take care of that. wouldent wanna restrict hot air right at the engine.

but either way, its 1/2 an inch, i dont see it make much of a difference, its still a high flowing downpipe.
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Well I ordered a ZZP 2.5 bolt-in with magnaflow cat, and a Intense pcm last night....now I play the waiting game lol.
 


sweet. you getting a plog? and im waiting on some roller rockers to come in. let me know how you like the intense pcm. i was thinking about an overkill but there locked, with an intense i could atleast have it dyno tuned and tweaked out a little more.
 
it doesnt bottleneck anything if you get a high flow cat with it. the overall power gained from getting a bigger downpipe outweighs going for the torque you get out of a 2.5" one.

i dont see why people go with small ones.
 
yea they said i would lose some torque with my pacesetters since they have the big primaries, nope, it pulls harder like down low in second its got a much better pull. dont feel like i have a dead spot anymore. they did hender top end performance a little. cant really get over 135 now but i dont really need to. plus rockers and pulley is gonna fix that soon :D
 
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