I pretty much spent all day on it today.

This started happening when I had the AMS inlet pipes installed (which I am supposed to review).

I am pretty sure that is the root cause of the problem, although it is certainly not due to any (direct) problem with the AMS product. I was warned when I got them that they would be a little long at the compressor inlet end as their Alpha28 turbos sit a little further towards the rear of the car than the stock turbos.

Fast forward through the installation process at Cobb Tuning Plano, they had a really tough time getting them to fit. For lack of a better way to describe it, the mounts are slotted which allow for a little play front/rear of the engine. I am pretty sure what happened was Cobb loosened those and ended up pushing the engine as far back in the mounts as it will go - you can see the "clean" metal under the washers. It has been moved an inch or a little more backwards.

Upon examining up in the rear bumper, my Europipe exhaust is coming back and contacting the rear bumper cover! It's actually wore a bit of a hole in the heat shielding back there where it rubbed. I haven't asked Steph @ Europipe about this yet, but knowing him I would be shocked if this was as intended. I'm pretty sure the engine being moved back caused it to start contacting the muffler cans, which act as an amplifier essentially and I hear this loud god awful sound coming out of the exhaust.

Now I just need to figure out what to do about it. I either trim the intake pipes and re-position the engine, or get the bigger turbos so the pipes fit correctly - then position the engine accordingly. I had been holding off making any changes until I understood what the noise was and what was causing it. I think we all know what I am going to do now .

I'm going to pull the rear bumper off the car tonight/tomorrow morning and test it to make sure that's what is doing it, but I'm 99.9% sure that's the problem.

 

Sorry I missed this, it was 100% e85.