jay14 Posted August 20, 2015 Share Posted August 20, 2015 Thinking of changing the up pipe on my wrx for an sti decat one because of the fear of potential problems with the cat damaging the turbo. My question is with mine already been mapped by prodrive would I need to get it mapped again if I removed just the up pipe cat? I'm not really looking power gains just want the car to run safe also don't like the thought of changing prodrives map :/ Quote Link to comment Share on other sites More sharing options...
baru Posted August 23, 2015 Share Posted August 23, 2015 Hey I was just thinking about this the other day not particularly for the failing cat but for a small increase in bhp did a bit of looking around. Yes basically, u will have to remap again after installation. If you alter/ change any flows of any substance to the engine a remap is required to maximise efficiency and engine longevity. Do you know the inside diameter of the sti pipe? As I'm mindful that you have to get right the kind of flow. Other forums have suggested the 3'' pipe would make turbo sluggish from less pressure against a smaller diameter pipe. Where would you get a sti pipe? I've seen a japspeed pipe 75 pound ish I'm thinking flexing pipe in the middle would be less stressful on engine as it jumps around under the bonet. Standard, I think its a solid one. Quote Link to comment Share on other sites More sharing options...
jay14 Posted August 24, 2015 Author Share Posted August 24, 2015 Not sure of size of the sti pipe, yea I have read about 3" affects boost, maybe someone here can confirm what the standard diameter size is Quote Link to comment Share on other sites More sharing options...
martyc Posted August 25, 2015 Share Posted August 25, 2015 The Perrin up pipe for standardish cars is 1.75 inch of i remember correctly. I've got an sti one yet to fit that I can measure when i get a chance if you want? Won't be til this evening tho Sent from my iphone using Tapatalk Quote Link to comment Share on other sites More sharing options...
jay14 Posted August 25, 2015 Author Share Posted August 25, 2015 The Perrin up pipe for standardish cars is 1.75 inch of i remember correctly. I've got an sti one yet to fit that I can measure when i get a chance if you want? Won't be til this evening tho Sent from my iPhone using Tapatalk Cheers, be interesting to see what size the sti one is Quote Link to comment Share on other sites More sharing options...
martyc Posted August 25, 2015 Share Posted August 25, 2015 It is indeed approx 1.75 inch Sent from my iphone using Tapatalk Quote Link to comment Share on other sites More sharing options...
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