im about to take of my prodrive exhaust system and replace with a 3" one and a decat. after fitting the new one will i need to remap straight away or will it be ok for a few months. its on an sti8 2003

 

I would say remap straight away, decats flow much easier which means your fuelling will be miles out.

 

You could experience problems with boost spikes when removing the downpipe cat. on the STi. Get it re-mapped ASAP or drive sedately, until you do.
JohnD

 

Hope this helps matey. I'm in the same boat as you.!

https://www.scoobynet.com/general-te...st-03-sti.html

 

Will probably get the CEL engine light come on. Keep it off boost until remap.

I thought the professionals told you to keep the prodrive cat.

 

Short answer is no. Fully decatting allows the engine to process way more air than it's fuelled for (even with the safeties of the factory ECU and PPP map) so as stated above, unless you run pretty much off boost, you'll be running the risk of serious engine damage due to the effects of running lean under load. Killing good old No. 3 piston due to it's position at the end of the fuel feed and closeness to the turbo/exhaust pipework being the probable area of destruction.
A full decat really has to be mapped in to safely maximise the engines performance.




I think thats what happened to my classic WRX, but was definately cause of my number 3 piston going onmy old Bugeye STI. Cost me a furtune

 

very funny gaz, they did now there changing there mind saying i will get most if the down pipe is 3", to increase spooling so i have now found a 3" from turbo back which is cheap. but its decat not sports cat. so what to do.
after reading robs thing im not going to do anything until its mapped in november hopefully, just buy the exhaust and leave it in the shed for now.

 

It's the best thing to do. In the meantime maybe worth wrapping the downpipe.