Decat help
 

Hi sorry if i have posted this message in a wrong thread. (iv never been on a forum before and also its my 1st impreza, any help would be much appreciated).
I have a 2001 bugeye impreza wrx, all seems to be running/driving fine. The question i have is about exhaust. I have stock upipe and stock downpipe. i want to keep them 2 pipes stock, but is it possible to decat the rear cat from the mid pipe (just after the downpipe) without a remap. Will it still run fine. I dont want to spend alot of money on mapping it. The truth be told i just had a new baby and the wife dont want me spending our money on my car YET. Just want it to be abit louder and pop and bang occasionally. Ps i already have a straight pipe and 4" backbox. Thanks for helping

Iv also been told by my local garage that the new age wrx ecu's are clever enough that they can handle decats without any problems.

You should be ok if you remove only 2nd cat. Just remember it is really recommended to remove pre-cat from up pipe as it has tendency to break apart and destroy turbo :)

HoodedLime. Thanks for your advice. I will remove the the cat. And if i fit a aftermarket upipe will it need to be remapped, as im worried about engine or turbo failure. Due to over boosting. Thanks

if you bin the 2nd cat and the uppipe cat I would at least get the car checked out before you go romping about the countryside too much. With the primary cat and standard downpipe in place you shouldn't be overboosting by much but it depends which map your car has on it.

The uppipe has an EGT sensor in it to measure the tiny cat - you'll want to remove this sensor when fitting the decat uppipe and either stick a resistor across the wiring terminals or leave the sensor tied up in the engine bay somewhere where it won't hit anything.

You'll get a little more poke from that, but nothing compared to what you would get with a proper map.

Thanks bludgod i think im goning to remove everything other then upipe and downpipe and backbox. 2 be on the safe side. So underneath the car will be a compete straight through pipe. Should sound amazing, without causing any damage, especially without a remap, I hope thats what everyone means. Thanks for all the input

no no - you want to remove the uppipe cat as well, they are known to break up and damage the turbo so that's why people remove them.

Rrr ok so its ok to remove everything other then the downpipe and thats 100% safe without a remap. Sorry if i sound abit thick lol

https://cimg3.ibsrv.net/gimg/www.sco...8dc16a121b.png

To be honest the only thing close to 100% safe without a map is leaving the car alone and filling it with super :)

But if you want to go for it then you want to remove the cat in the uppipe and the 2nd(rear) cat. Keep the big one in the downpipe to keep you right come MOT time. The uppipe cat has a sensor in it so just keep the sensor attached to the wiring and tuck it out of the way (decat uppipe doesn't need the sensor). When you get the car mapped then you can disconnect the sensor and bin it.

Keeping the sensor attached stops you getting a code for the uppipe cat not being there, keeping the main cat stops you getting a code for the rear o2 sensor so you'll still only be making standard boost (maybe a little bit over standard but the ECU will try to wind it back to standard for you). You won't see the best performance from this but you'll get a tiny gain from it - if you can't afford the map can you even get it checked over somewhere? Just a quick blast on the dyno to check fuelling and knock are all OK.

Wow thanks that was very helpful.. When i do get some money together i will be putting a front mount intercooler and a dyno remap. But for now is it worth getting a cheap flash remap for only £150

i wouldn't bother with the frontmount, look for an STI topmount (with the air deflector to suit), decent panel filter, fuel pump and a boost gauge. The TD04 is so small your just wasting time trying to fill a large frontmount and all the extra pipework.

With regards to the remap, it's not about the cost it's about the quality of the tune so make sure and do plenty of research before committing to a purchase. There are plenty of good mappers about you on the mainland so you'll get your monies worth if you save up and get a good job done the first time.