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Hi everyone,

I tried to search but could not find the answer.

I believe the HKS Kansai Resonated mid pipe is 85mm. Anyone know whether this will directly bolt to the stock exhaust without leaks/problems?

?????????????GT-R

thx. :)
 

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My only questions is why would you want to bolt a 85mm Y-pipe into the standard 70mm exhaust?

That mean there will be a 15mm difference in diameter where the Y-pipe meet the exhaust, and the exhaust flow will hit a wall when that happen.
That would seriously disturb the exhaust flow.

If you are using the standard rear exhaust section, then at most use 75mm (3") exhaust if you don't have much choice.
But the best choice will be using the same diameter (70mm) as that ensure smooth flow with no bottle neck.
 

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HKS Y pipe

I have the HKS Kansai cutback , but I know like say lots of the 90 mm downpipes narrow down to connect to the Y pipe , not sure which they are , maybe on the Y pipe to cutback the same happens .
 

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I have the HKS Kansai cutback , but I know like say lots of the 90 mm downpipes narrow down to connect to the Y pipe , not sure which they are , maybe on the Y pipe to cutback the same happens .
The problem is most large Y-pipe are design for larger cat-back system.
So unless they taper down slowly, which I doubt due to the bend at the end of the Y-pipe, then it is going to majorly disrupt flow when you suddenly take out 32% of the surface area by going from a 85mm pipe into a 70mm pipe.

Even going from a 3" (76mm) Y-pipe to the standard 70mm exhaust, it is a reduction of 15% in surface area.
 
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