Will I lose or gain from a dp?

Q&A regarding engines, turbos, and intercoolers and power upgrades

Will I lose or gain from a dp?

Postby celigts » Thu May 10, 2012 10:50 pm

So my stock dp is gutted but I hate how big it is so all I can find are 3" dp's online..

I have 2.5" exhaust from dp back so will I lose if I added a 3" dp to my stock setup. ?
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Re: Will I lose or gain from a dp?

Postby monkninja » Thu May 10, 2012 11:44 pm

I have no experience with dynos myself, but from everything I have read our car will have more power with a 3" exhaust. Most people's first exhaust upgrade is a down pipe, and they will have gains, of course they don't usually have gutted cats, but I am sure that the mandrel bends of a 3" down pipe will improve air flow. Right now I am running turbo back 3" exhaust including a down pipe (except for the freaking mid pipe :bangshead: because it is so expensive!) and it feels a whole lot better than it did before! But as far as I have seen from people you will only gain by getting a down pipe.

Hope this helps!
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Re: Will I lose or gain from a dp?

Postby Corey » Thu May 10, 2012 11:47 pm

Ko Racing makes a 2.5" downpipe
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Re: Will I lose or gain from a dp?

Postby toayoztan » Thu May 10, 2012 11:53 pm

Usually people upgrade the dp, that's it. When that happens, you create a bottle neck. What's worse is, the mp has a secondary CAT which is usually clogged or restricting.

Replacing the MP too helps a bit.

If you have a 3" exhaust system with a gutted CAT, you will see "some" gain going to a 2.5 or 3"...more in the spool of the turbo, espcially if you have a boost controller.

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Will I lose or gain from a dp?

Postby celigts » Fri May 11, 2012 12:22 am

Corey Darling wrote:Ko Racing makes a 2.5" downpipe


That dp is also almost 300 without shipping. Not sure I'm looking to pay that much but I do wanna keep the exhaust true to the 2.5" instead of going 3" do and 2.5" full exhaust.
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Re: Will I lose or gain from a dp?

Postby l00k0v3rth3r3 » Fri May 11, 2012 2:04 am

i had 3" all the way back and then 2.5 to the stock muffler...loved it...had zero problems, and kept away from the buzz cannon look
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Will I lose or gain from a dp?

Postby celigts » Fri May 11, 2012 2:33 am

Any noticeable difference? Deeper tone or lower bottom end?
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Re: Will I lose or gain from a dp?

Postby l00k0v3rth3r3 » Fri May 11, 2012 2:40 am

it was all straight pipes no cats, and no i didn't really notice much...it did have a nice tone to it, but on the way to the shop i was running a straight dp to nothing that was loud! haha
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Re: Will I lose or gain from a dp?

Postby 4rsnduction » Fri May 11, 2012 3:11 am

Before i got my exhaust fully completed i had just a 3inch downpipe connected to the stock 2.5inch exhaust system.
It bolted up perfectly, did not leak and most importantly improved response noticeably.
While the exhaust didn't sound louder from outside the car.....from the driver seat the tone was much deeper.
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Re: Will I lose or gain from a dp?

Postby lumbercis » Fri May 11, 2012 3:15 pm

In terms of power I wouldn't worry about having a 3" into 2.5" system because at the level of power you are at on the stock turbo it's not going to make enough difference to feel. Yes, theoretically it's not best for flow to neck down, but I'd be surprised if it caused you to lose any hp at all as you are still likely removing overall restriction over a gutted cat. Unless you have the stock turbo maxed to the gills you probably aren't even using all the flow a 2.5" system provides.

In short, throw the 3" on and don't worry about it. If you upgrade the turbo later think about redoing the exhaust to a full 3" system.

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