Finally got my midpipe installed two days ago. Took a lot of work and time and I ended up having a shop blow torch a bolt and both O2 sensors off since they were rusted and tightened like crazy. When I started my car up for the first time, it scared the crap out of me how loud it was, especially since I was in my garage! After inspecting, I found the bolts after the cats and at the axle were still a bit loose. Right after tightening them, it got much quieter. Almost like stock except it sounds nasty when revving. I looked under the car and noticed hot air around the cats, there's a slight 1-2mm gap between the cat flange and midpipe connection. I tightened the bolts completely though.

Is it normal to have a gap between the cat and midpipe flanges? I'm guessing it's cause of the gasket but not sure.

 

You will have a small gap that the rubber gasket will seal it though.

Do you have an exhaust or stock exhaust with invidia mid?

 

That should be good. I was curious about this too since I have the invidia and megan drift spec combo and couldnt find a reason why my setup sounds quieter than some other memebers'. I lifted my car up and saw that there was a small gap between the exhaust and the midpipe. It is sealed by the rubber gasket however. You should be alright

 

I looked at the stock pipe and noticed how the flange for the connection to the cat is cut in a bit for the gasket while the Invidia isn't so I guess a gap is normal because of that. However, it feels and sounds like there is a leak somewhere but not sure where. I feel warm air around the cats but not enough to be sure if it's normal or if it's leaking there. Everything is tightened.

For now, I got a stock axle-back. I drove around a bit with the midpipe not connected to the mufflers and it's quite loud. So I decided I'm going to do straight-trough mufflers with dual tips each for quads sometime within the next two months or so.

 

Did you car have any backfire when riding without your stock exhaust

 

You point out something interesting, when driving to school this week, I was stopping at a light and heard something. I thought something fell off my car, maybe my roof spoiler or something perhaps, but nothing did. I turned off my music and when I was coming to a stop at the next light, after going back into first gear, I heard a muffled popping sound. I tried to replicate it again and it did the same thing. This happened with the stock exhaust connected BTW. So yeah, it does a quiet backfire when changing back to first gear. It doesn't sound good though and I can't tell if smoke/fire comes out since I'm driving but I highly doubt that.

 

Uh! What does this invidia mid give you .. ? Just curious ..

 

^ sound and about 2hp

 

The exhaust pop on deceleration happens on mine as well, stock mid pipe, Lexus HKS cat back.