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clarification of boost spikes and exhuast changes

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Old Aug 3, 2010 | 01:48 PM
  #1  
l2iceman's Avatar
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From: Canada
ON clarification of boost spikes and exhuast changes

Hey guys,

ok, so I'm picking up my rx-7 this week sometime...very excited, i've been on the forums for hours the past few days reading and reading...

so the car itself has an exhaust, not sure what kind, not sure what's been replaced as the owner doesn't know himself, he is an older gentleman, brought the rx-7 to a local known Toronto area rotory shop(Mazdees in Pickering) for regular maintenance, and they recommended that he change his exhaust and intake to gain more power. Now, from what I saw, the stock airbox was removed and two K&N intake filters were put on it, the intake arms are still stock from what I can see, unless the K&N are very stock-ish looking lol...

anyway, so yea, i'm not sure what parts of the exhaust were replaced, but I"m assuming that if it was Mazdees that recommended it, they did the modifications in a safe manner...

so just to double check, as i'dl ike to be sure before i drive the car 2hrs back home...

if the STOCK CAT converter is still there, whether downpipe has been changed or not(i know it's a cat-back for sure), with the stock intake arms, I should be safe right?

I read through the FAQs, did some research, i've read that it's ok as long as the stock cat is there...

but I also read on several threads that the stock cat or high-flow cat would only help in preventing the boost spike...and not for sure, meaning I should also get a boost controller...

so just asking if anyone can clarify this...

As long as the stock cat-converter is there, I should be ok? or should I get a boost controller as well...

what if there is a high-flow cat? am i ok as well? as the high-flow cat still is a restriction...

thx.

PS while on subject, what if i was to replace the intake arms and install, say GReddy intakes? am i still ok with the stock cat or high-flow cat?

bytheway, I do NOT intend to take the stock cat or highflow cat out if it is there...I'm actually hoping that is the case as I want to be as reliable as possible...
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Old Aug 3, 2010 | 03:28 PM
  #2  
Aaron Cake's Avatar
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From: London, Ontario, Canada
It sounds as though you are looking at a 3rd gen? You didn't specify, so I am guessing...

You should be fine if the stock cat is still in place. If it isn't, and you upgrade the intake/exhaust, you are probably looking at boost creep. Porting the wastegates will help somewhat but there is limited room to port them.
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Old Aug 4, 2010 | 08:48 AM
  #3  
l2iceman's Avatar
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From: Canada
hey Aaron, thanks, yes I read about porting the exhausts but that is alot of work since the turbos have to be removed. I'd like to go reliable and cost effective - which to me is simply keeping the stock cat(if the car has it, I'm bringing it to a shop when I get back home with it)

my concern is when people say "should" lol considering all else is running fine and dandy, am I safe, or is it still a gamble? lol I don't plan to track the car(for now), or drive it hard, maybe a spirited drive here and there, but other than that I just want it to run well as a summer daily driver as I do not plan to modify it any further(maybe upgrade suspension).

thanks~

PS. I slowly will be doing reliability mods, such as a larger intercooler, ducting, install a 2nd oil cooler, upgrading rad, replacing AST, etc.
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Old Aug 4, 2010 | 03:51 PM
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97SupraTwinTurbo's Avatar
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From: glendale, ca
From what I remember, the front pre-cat's need to go. The main cat is the one that reduces emissions and reduces noX and CO2's and carbon deposits. The front cat usually gets clogged. The pre-cat glows when driven hard. Try cooling mods since the cooling system isn't done up too well.
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Old Aug 4, 2010 | 04:30 PM
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dgeesaman's Avatar
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Boost spikes or changes in steady-state boost level can happen in FDs with two or more mods. While it's less likely with a stock cat it can still happen depending on the other mods. I strongly recommend installing one for any car with an intake, downpipe, and muffler. This way you can keep your boost at 10psi until you upgrade tuning and fuel system appropriately.
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