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I know there's the issue of removing the cats causing the turbos to fail prematurely, but would it be a possible solution to remove the cats and replace them with silencers instead, to try and maintain a small amount of backpressure to help protect the turbo seals whilst still gaining some of the advantages of a less restrictive exhaust system.

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So what is this turbo problem with the decats, that was definately on my top 10 mod list, now i'm scared. Who's had this problem, how do u sort it & what's the genral verdict on fixes??

So what is this turbo problem with the decats, that was definately on my top 10 mod list, now i'm scared. Who's had this problem, how do u sort it & what's the genral verdict on fixes??

 

kills the turbo seals according to some, like i said, some people have had no problem where some have had a problem. there was a thread not so long ago with a poll

  • Author

do a search for the problem.

 

i don't want to take the risk of killing the turbos, but would like to make the exhaust less restrictive. hence, can i replace the cats with silencers?

if you're replacing it with something equally restrictive, then what is the point? :confused:

i have removed my cats and silencers about a month ago and the difference is amazin, i got told that the turbos that go were probably on there way out anyway but doing the mod just speeds up the aging process

Evidence seems to show that when you decat and get smoke it was becuase the Turbo seals were already gone and the cats were hiding it, or they were just about to fail and the backpressure loss was the final straw.

 

The difference in performance/response is very noticable with a decat, and while most have not had any problems. some have.

 

Replacing the cats with something else restrictive would be pointless. You can get Performance cats, but they are expensive. Will give slightly better response, but could also give just enough less backpressure to cause the turbo seal problem anyway. Its all or nothing Im afraid.

The car will run a lot better and be more responsive without Cats...............but most 15-16 year old turbo seals can't handle the extra back pressure and fail either straight away or shortly after. If you've got the spare money to change the turbos then go for it, if not I'd leave well alone.

i removed the cats and put a central balance box in to stop the boooming on the motorway ...or lessen it ..no probs with the tubbies yet it was over a year ago

cats are way more restrictive than a silenced box so you will gain , the response difference and spool up is very very noticeable .........the LACK of backpressure is what causes the tubbie seal to fail isnt it .........anyway Kirbz and his wizzard mechanic Dad are fitting some big bad boys and injectors , and internals for me in september so if they go now WTF :)

see my poll on this subject, shows numbers of who had problems and who didnt.

 

http://www.300zx.co.uk/forums/showthread.php?t=74882&page=2&highlight=decat

 

I'm still going to decat mine, but at the end of summer so if it does kill it i will have all winter to change the turbos. I'm going to get my own custom decats made with boxes and maybe some small restrictors. No there wont be as much performance increase as a straight through but better than 15 year old clogged up cats!

  • Author

i have a jap system on the car, stainless steel from turbos back, 1 cat each side, then joins into a small silencer, then into single backbox.

 

i'm definately going to get the small silencer removed in the future, i would like to decat because of the performance gains, but concerned about the standard tubs. the car has done 33500 miles, i'm first uk owner with no history for car. all performance mods, except exhaust & bov's, removed before import.

 

i think i'll save up for new tubs before i do the decat, then i won't be fooked if the tubs die.

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