GEN 2 Kooks 3in downpipe Availabe

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solarwinds

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DrifterGTR

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hard to consider since it sounds like a crazy woman.. just saying

also i'm no mechanic but what does .25" more than stock get you if the turbo exit is just 2.75 at max ?

It's all about removing as much back pressure from the exhaust system as possible as quickly as possible. A larger diameter pipe allows the turbo to spool more easily, and thus more power sooner. With turbos our size the reduction in spool time isn't all that great, though it is there and it leads to a legitimate gain, just not a huge one. Maybe 10 HP or so. But, once you start moving into larger turbos or hybrid aftermarket solutions, larger compressors or variable geometry vanes on the turbine side, ect, you can find some really interesting power potential in a pretty small package. But ideally you want the entire system to be equally sized.

Just to explain a turbo or boosted engine really quickly , the turbo is in effect an artificial engine displacement enhancer. Engines are designed to move a certain amount of air. In our case 3.5L per full rotation of the crankshaft. With a turbo delivering 14.7 PSI at sea level that engine is now effectively 7.0L based on the amount of air it's moving. Beyond that say at 30PSi it's roughly 10 Liters ( Someone check my math I might be off). But there comes a point of diminishing returns based on how the turbo is designed. You couldn't necessarily strap a single Garret T76 Turbo onto our engine and expect to run 25 or 30 PSI. There is no telling where the boost would come on or what the spool characteristics would be like. The turbo could take it for sure, but the engine might not. Ultimately you have to read the compressor map to properly choose a turbo; plus you'd need supporting mods like a fuel pump,injectors, map sensors. custom tune, and a stronger intake depending on exactly how strong the stock intake is. Plus you'd need to at a minimum put in some head studs. I've gone this route before. It was worth it, but it's was a huge PITA .But I'm way off topic now.

Anyway, that relatively small change in diameter can make drastic differences in power delivery. Additionally, there are some benefits in reducing exhaust gas temperatures as well. But overall the less restriction you have in any boosted engine leads to an engine that has less overall stress on engine components, more power potential and in my opinion a better sound.
 
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Dachuri

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@DrifterGTR. The SPD Turbo Adapters make a similarly small increase in diameter, believe it's also somewhere around a 1/4". What's your thoughts on the SPD's performance impact?
 
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DrifterGTR

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@DrifterGTR. The SPD Turbo Adapters make a similarly small increase in diameter, believe it's also somewhere around a 1/4". What's your thoughts on the SPD's performance impact?

I don't personally have them, but they are something I have considered getting. Though, I like uniformity, and its killing me that there isn't a complete solution from the turbo's back already. IMHO that's when the real power is going to start being found. That said you could also port the stock adapters were you inclined to do so with a dremel tool and a carbide bit, or maybe even a good hole saw. All it would take is a template and a steady hand. It's not as fancy as a store bought part, but it wouldn't need to be perfect either.

As far as performance is concerned adding them to a stock exhaust probably bumps you somewhere around 5 HP, but you still run into the issue of that reduction in exhaust tubing diameter. Think about water running through a pipe, If you have a 1 inch pipe and you suddenly transition that into a 2 inch pipe you'd lose pressure, because you can move the more water through the larger pipe. on the flip side of that going from 2 in to 1 in would increase pressure but lose volume. With a turbo or boosted applications you want volume more than pressure. The faster and easier you can get the exhaust gasses out of the engine /exhaust system the easier it is to make more power. Both pipes would get the job done, but ultimately the bigger hole make for an easier removal of exhaust gases.

Basically, small to large pipe is good, and large to small is bad, But ideally, you want a single size solution for optimal performance..

---------- Post added at 10:31 PM ---------- Previous post was at 10:28 PM ----------

I actually have an image of both. The factory one has weird variences.

...

variances, or some basic porting so its not a straight hole cut into some cast iron?
 

nikhsub1

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@DrifterGTR. The SPD Turbo Adapters make a similarly small increase in diameter, believe it's also somewhere around a 1/4". What's your thoughts on the SPD's performance impact?

Doesn't matter since you are pushing though ****** restrictive OEM cats... It may give a bit more power and better throttle response but at the end of the day the OEM cats are the biggest restriction.
 

SterlingE55

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These will be my choice due to the fact they'll still pass emissions and the kooks cats seem to flow the best out of the HFC cat options.
 

MacG

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got mine pre ordered already trying to decide if i should get SPD Turbo Adapters as well
 
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