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Old 10-17-2012, 12:08 AM   #7
Scooby Newbie
Member#: 200057
Join Date: Jan 2009
Location: near St Paul, MN
2013 Impreza 2.0i
RalliSported RomRaided


Originally Posted by GEE-OTTO View Post
Nice work, as usual What the big differences, if any btwn the FB20 and the EJ253 stud spacing wise? It appears that the layout is fairly similar from the prototype.
The dual port flanges I have made for the 2.5i fit perfectly on the FB20. The overall distance from one side to the other seems to have increased by 1-2mm. What's odd is that it almost appears that whoever designed the factory exhaust manifold didn't take this into account, as my factory unit was pinched too tight and had to be pried on and off. It started to booger up the threads on the engine studs, which I wasn't very excited about.

The bolt circle diameter on the three bolt flange has been increased (which is why I had to hack up one of my off the self 2.5i flanges to make it fit, until I get some custom ones made). Also, the angle of attack of the three bolt flange is slightly different: on the 2.5i its roughly 15 degrees from being perpendicular with the engine, on the FB20 its only about 5 degrees.

Originally Posted by MjSub2.0 View Post
Please shoot a video when you try it out. Excited to hear the sound.
I'll replace the factory mid pipe (and pancake resonator) with a custom mid pipe first. I wasn't too impressed by the rumble with just an axleback.

To all those seeking rumble for their 2.0i PLEASE NOTE:

I'm not trying to turn away sales, but since the 2.0i already comes with that wonky "Lakester" style collector, it's inherently a UEL design and you can gain at least a mini rumble by simply bolting on an axleback or full catback (both of which I'm also developing). So spending $600 on a aftermarket UEL just to gain a little more rumble seems redundant and pricey, (but hey, if there is enough demand, I'm more than willing to make one for that purpose!). Therefore, I will be concentrating on building a performance header while still retaining a UEL design (to satisfy the demand for rumble). The header I posted pics of is simply a starting point, I can lean more toward the peak hp side or toward the lower end tq side. I can stay 4-1 or go 4-2-1, experiment with piping diameter and lengths etc etc. Honestly though, I mostly put this header together to see how long I can run a HFC on a PZEV model before it throws a cel.

Originally Posted by Wes_888 View Post
Dammnnnnnn these look awesome!

Will you be considering doing a dyno run for stock vs your exhaust setup for comparison?
Absolutely! My goal is to come up with a header/cat delete pipe/catback combo that reclaims the 20chp the base Impreza lost when going from the EJ253 to the FB20. Hey, its good to have goals...
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Last edited by blk6s; 10-17-2012 at 12:45 AM.
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