k swap exhaust options


scottk054

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Feb 15, 2015
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Looking for advice, I love the spoon n1 system and wanted to go for that but I seen alot of comments about 3'' system being the best. Question is, is a 3" system going to have a big power difference to a 2.5" spoon system?
 
3inch seems to be good for k-series, a mate of mine had it on his dc5 and seen some good gains.
 
3" works well on a k20. I have a 2.5" at the moment. I don't know what the difference would be in BHP however you would expect to see and increase at the top end of the rev range.
 
Yeah I know it would be better but just wondering if there's a big diffrence as I would love to stick with the spoon n1 if it's not going to make a big diffrence
 
Stick with the spoon and enjoy it.
Unless your chasing numbers out of your k20?
 
I've had 2.25, 2.5 and 3" systems on mine and there isnt that much diffrence.. the smaller feels better low down but stuggles after 7.5k the 3" better 7k+ but loses out under 5k.. I have no numbers to back this up, its just what it feels like to me...
 
High numbers is good but I think I will just go with the spoon :) thanks for the help deciding.
 
Mine made 196whp on 2.5" - everything else stock bar a 4" Blox filter and custom intake. You can see where a 3" exhaust would help higher up in the rev range though:

 
Well I have stage 1 cams in my engine and going to get ITB's and a 4-2-1 manifold so I've no idea what the diffrence would be with a 3" but I've have a spoon n1 on my ek4 and ep3 and lover it!
 
If your going cams and ITB I'd run a 3" for sure!

I'll be going up to a 2.75" or 3" when I put stage 1 cams in my B18C and get it mapped again.

Just get a custom 3" with a spoon n1 style back box :nice:
 
If your going cams and ITB I'd run a 3" for sure!

I'll be going up to a 2.75" or 3" when I put stage 1 cams in my B18C and get it mapped again.

Just get a custom 3" with a spoon n1 style back box :nice:

FWIW I fitted a 3" system to my old DC2 and it did not like it... I'd stick with 2.5" on a B series for sure.
 
FWIW I fitted a 3" system to my old DC2 and it did not like it... I'd stick with 2.5" on a B series for sure.

My tuner recommended a 2.75 as that's what most people in Ireland run with decent powered b18c with cams etc... My 2.5" is already slightly restrictive right up at the top of the Rev range.

If your going proper high compression b18c then I'd go 3" but don't think I'm going that far. It's all about how good the map/tuner is anyway :)
 
2.5" flows enough for 250bhp.. dont see many b series up there.
 
would a 3" not be too loud for the track? Obviously no point putting a silencer in. There's a 2.5 inch straight through with spoon n1 back box for sale I was thinking about but still undecided.
 
All depends, silencers/mid boxes don't restrict any power as long as they are the same diameter at the exhaust :)
 
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