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decat/ downpipe

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  • 1 month later...

If I remove the 1st cat do I need to remap?  Just bought the car and prior to buying it was running at 0.5 bar boost, the issue was the 1st cat was blocked, I was told it was sorted how do I know??? If it hasn't would I be best off replacing the downpipe from the turbo with a cat free pipe?? Hence the first question



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0.5 BAR will feel sluggish. 


Put a sports cat downpipe on it, that way you'll know if you make target boost as it'll feel rapid and it'll run a bit safer until you get a remap. 


A quick test to see if you can make boost is to pull the vac hose off the actuator nipple when the car is warmed up during the hottest part of the day and floor it in 2nd gear. The car should make around 1.4 bar. Don't floor it in 3rd gear upwards as you'll most probably get a violent fuel cut.


If the car feels much faster then you know you don't have a bad boost leak, "blocked cat" or stuck open wastegate etc. 

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Yes, asap. You can run without remap for a time if you stay off boost. 


Decatting without a remap won't give much power just a quicker spool time, boost spikes with the chance of detonation and a CEL. If you remap after decat the car will generate up to 20bhp, run far safer and probably more economically. 

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