TheDon427 Posted July 6, 2011 Share Posted July 6, 2011 I have a 3" Magnaflow catback and just purchased a 3" Invidia catless downpipe. Will I need a 2.5" - 3" adapter or will the flanges mate up? I know some 2.5" exhausts have a 3" flange to mate up with 3" downpipes but I'm not sure if the Magnaflow has that feature. Can anyone clarify? Link to comment Share on other sites More sharing options...
mr.hicksta Posted July 6, 2011 Share Posted July 6, 2011 Yeah you should get an adapter because the Magnaflow necks down to 2.5" briefly after the flange. I didn't use one and smoked many gaskets. Hit up M Sprank with Infamous Performance. I got the adapter/gasket/donut from him. Link to comment Share on other sites More sharing options...
TheDon427 Posted July 6, 2011 Author Share Posted July 6, 2011 Thanks for the heads up. I just posted in his thread. Link to comment Share on other sites More sharing options...
fahr_side Posted July 6, 2011 Share Posted July 6, 2011 Invidia DP is a flat 3" flange. If you bought a CBE necked down to 2.5" you could use an adapter, but then you have a small choke there... 3" > 2.5" > 3". I had the same problem... also an Invidia DP... the shop that made my midpipe screwed up and necked it to 2.5". I had them chop off that 2.5" flange and weld a short 3" pipe and flat flange in there so it's 3" all the way. Let it breathe! Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs. Link to comment Share on other sites More sharing options...
mr.hicksta Posted July 6, 2011 Share Posted July 6, 2011 ^^^Â I agree. That's probably the best way to go about it. Link to comment Share on other sites More sharing options...
MasAyinde Posted July 6, 2011 Share Posted July 6, 2011 http://www.stickergiant.com/Merchant2/imgs/450/hss255_450.jpeg Running a free flowing TBE is the #1 cause of boost creep and porting the wastegate will help prevent it. Link to comment Share on other sites More sharing options...
TheDon427 Posted July 6, 2011 Author Share Posted July 6, 2011 I think I hit boost creep a total of 3 times during the 135k miles I owned my '06 WRX. It was fully catless from around 10k miles and on. It only happened when I had my electric cutout wide open. Link to comment Share on other sites More sharing options...
bmx045 Posted July 6, 2011 Share Posted July 6, 2011 i have a magnaflow cbe and an invidia 3" downpipe, no adapters needed... Link to comment Share on other sites More sharing options...
omnicron Posted July 6, 2011 Share Posted July 6, 2011 I have one also and it meets up pretty well. The Magnaflow was designed for 2.5-3 and bolts up reasonably well. The best was to use the subaru silicon stuff they use when they build engines... it sealed up better than the actual gasket. Link to comment Share on other sites More sharing options...
TheDon427 Posted July 6, 2011 Author Share Posted July 6, 2011 Great, those were the responses I was looking for. Thanks, guys. Link to comment Share on other sites More sharing options...
bmx045 Posted July 6, 2011 Share Posted July 6, 2011 Yes, grab some gasket maker silicone at autozone for the connection, they bolt together fine but I noticed the gasket wasn't enough to create a good seal...I was smelling fumes and pulled the gasket out, lotta leak spots. So go generous with the gasket maker...use it in conjunction with the supplied 3" gasket...it works real well. Link to comment Share on other sites More sharing options...
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