Hey guys, i was helping a buddy of mine install a megan turbo back exhaust on his evo 9, and when i was installing the downpipe, i noticed that when the bolts were fully tightened, there was a gap between the flange on the dp, and flange on the 02 housing. I also noticed that it seemed like the 02 housing was too big in diameter to fit in the dp. Seemed like the dp was not fitting on the 02 housing correctly. Could it be possible he got the dp for an evo 8? With the dp installed it rubs on the brace right underneath the dp. What do you guys think is wrong?

 

i dont know but we had problems with the megan cat back and exhaust mani once when i first bought my car. never went back to them....

but yeah check to see if there is two different setups for the VIII and IX

 

their shouldnt be a difference since many if not all exhaust are for viii and ix together.. i could be wrong though

 

Maybe due to the ACD unit that the IX's have in the path of most VIII's downpipes?

 

Pics would help out some. But as far as the DP goes, yes the VIII and IX ones are different. The VIII does rub on the cross-brace and a couple of other places as well, if I remember correctly. And I couldn't imagine a DP not mating up to the OEM o2 housing. Are you using the gasket Megan supplied or the OEM? I know the OEM gasket usually fits better than Megans.

 

try using a few washers on the lower brace to get more clearance between the dp and the brace. 3" dp's sometimes have this issue. after the dp is clearanced, start the car and check for exhaust leaks between the dp and o2 housing flanges. if no exhaust leak and nothing is touching under the car, you maybe fine. check again after a day or two of driving.

 

what you are seing is the doghnut seal on the o2 housing protruding a little bit outside of the flange seat on the down pipe,,,, thats ok as long as you get somewhat of a seal between both pieces.
i noticed the same on my car,,,,,, just make sure that when you are torquing the spring bolts,,, you go the equal amount of turns on each one of them,,,, for example 5 turms on bolt # 1 5turns on bolt # 2 so and so forth until you rreach full torque


you see what i mean burn

 

/\ Yes, if you have the donut gasket in like you should with a IX downpipe, you will see a "gap" just like the OE pipe (harder to see), but it will be sealed just the same.

As for rubbing... there IS a downpipe for the non-ACD (flex section) and a DIFFERENT downpipe for the ACD (no flex section) cars. Sometimes you can get the non-ACD pipe to fit an ACD car, but Megan specifically designed a downpipe for the ACD cars after they hit our shores. Distributors are aware of this, however, unfortunately there is a higher profit margin on the non-ACD pipes so you can guess what motivates some.

 

If all else fails, take it to a muffler shop. They should be able to fix you up.

 

Alright thanks guys. So there should be a gap between the flanges caused by the 02 housing donut, but its still sealed correctly? Ill have to recheck everything, but i didnt reuse the spring bolts, i used regular bolts that came with the exhaust. Should i be using the spring bolts?