HawkSTI Posted September 24, 2017 Share Posted September 24, 2017 I've been looking at getting a straight through centre section for my 2006 hawk sti, to mate to my prodrive backbox. The main reason is so I can delete the big silencer and hopefully have a little bit more noise while keeping the subtle look of the prodrive unit. I believe there is a catalytic converter in the down pipe and another between the down pipe and centre section. All the straight through centres ive seen are listed as 2001-2007, so replace the 2nd cat as well as the centre silencer. My question is, if I replace this cat and silencer with a straight pipe, will the car need mapping straight away? Ive read some conflicting opinions on this, people saying that as long as the up pipe and downpipe still have the cats in then it will be fine; while others say that it will need mapping straight away. What's people's thoughts? Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 Me personally, I'd do as prodrive did and leave the one in DP and bin the rest. If I remember right, wrx has 3 cats, STi 2 and prodrive 1Sent from my HTC One M9 using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 @mattiekane cheers mate! so as long as I leave the ones in the up and down pipes, it will be safe and legal to bin the centre one? 😁 Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 Ur an STi, you only have two, buy a non res centre pipe and you will be fineSent from my HTC One M9 using Tapatalk Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 @mattiekane I see where your coming from, but; I thought the 2006 sti had a cat in the down pipe, then a small section between the centre and downpipe with another cat, then the resonated centre section then back box. All the centres ive seen are for 2001-2007, so replace the 2nd cat and deresonated centre. On 2001-2005 cars the 2nd cat and centre is one pipe. My question is, is it safe to replace the 2nd cat and resonated section with a straight through section without having it mapped, as long as I leave the one in the downpipe? Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 I'd would of thought you would be fine,@Tidgy would probably know better thoSent from my HTC One M9 using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 Cheers @mattiekane 👍👍 Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 I think it's removing all the Cats is where the problems start, other option of course(to play it safe) would be full decat an map, then you know it's right regardlessSent from my HTC One M9 using Tapatalk Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 Or buy a blitz lolSent from my HTC One M9 using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 @mattiekane my plan is to make it a bit louder, but keep it legal (I.e so it can pass an mot) and not to **** the neighbors off too much when I start the car at 5:30am and leave it 5 minutes to warm up 😂😂 i guess that pretty much rules out a nur spec lol Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 Sod the neighbors, Impreza's are meant to be loud and abuse the ear drums, imagine how mine feel at 6am lol and I have a decat waiting as soon as I can get a map on itSent from my HTC One M9 using Tapatalk Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 @mattiekane which cat are you taking out? Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 The last one in my downpipe but only when I can sort a map for itSent from my HTC One M9 using Tapatalk Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 24, 2017 Share Posted September 24, 2017 Loud pipes save lives [emoji16]You could always just buy a subtle looking back box thats a bit louder than the prodrive Sent from my SM-G930F using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 @savage bulldogs I did think of that, but with the centre resonator still in place, the backbox alone wouldn't make s great deal of difference would it? Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 24, 2017 Share Posted September 24, 2017 Prodrive boxes are renound for being 1 of the quietest boxes out there but ive never tried tbh Sent from my SM-G930F using Tapatalk Quote Link to comment Share on other sites More sharing options...
Sandals Posted September 24, 2017 Share Posted September 24, 2017 You won't need a remap as long as you're not touching the downpipe. I did this mod and ran it for about a year with zero issues, as long as you get a cat pipe section which has a hole for the o2 sensor you should be fine. Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 15 minutes ago, savage bulldogs said: Prodrive boxes are renound for being 1 of the quietest boxes out there but ive never tried tbh Sent from my SM-G930F using Tapatalk @savage bulldogs yeah it's very quiet. It sounds as though the cars cut out when you come to a junction it's that quiet, and it's not a great deal louder once you put the toe down. Thing is though, I like the way the prodrive one looks on the car. I thought a straight through centre would wake it up a bit but I don't want any problems. I suppose a subtle but louder back box would do the trick. What do people normally go for? Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 @Sandals thanks, good to hear👍 How much louder does does it make the car removing the centre silencer and cat? Quote Link to comment Share on other sites More sharing options...
Tidgy Posted September 24, 2017 Share Posted September 24, 2017 Should in theory be ok if your not removing all the cats, but its always worth getting it dyno'd after to make sure all ok. Most cases its fine but no way to be 100% sure without checking Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 I was running a cat back straight pipe for a bit, that sounded awesome.....sometimesSent from my HTC One M9 using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 @mattiekane just bought a straight through centre pipe 🏎💥💨 1 Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 Jesus, about time lolSent from my HTC One M9 using Tapatalk Quote Link to comment Share on other sites More sharing options...
HawkSTI Posted September 24, 2017 Author Share Posted September 24, 2017 Keeping the cat in the down pipe and keeping the prodrive backbox, but the mid section will be all business, milltek stainless straight through job. Not sure how loud it's going to be, but no doubt a touch louder at least 😎 Quote Link to comment Share on other sites More sharing options...
mattiekane Posted September 24, 2017 Share Posted September 24, 2017 Will probably sound wellSent from my HTC One M9 using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
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