Exhaust System Upgrade Options Available for Turbo I4 AMG Engine Yet?

[675430VME]

Damn, I was thinking about tackling this install myself when I get back to the states, maybe i still will since removing the downpipe seems to provide better access to some of the exhaust specific clamps.

You can probably ask Boomgear to show you when you come visit. They are able to take it out very quickly if you know how.

 

[675430VME]

That should definitely increase volume. The downpipe is a major bottleneck.

Totally agree, in real life the difference is day and night but its hard to capture the sound without proper equipment.

 

[Aerie]

It’s just a page in the Lotus diagnostic software. They go to the page in the Lotus software, select the exhaust valve calibration and press go. The valve goes to full open, full closed and the car learns the new open/closed positions of the valve. That’s it, very simple with the correct software.
I believe the Milltek Exhaust valve controller avoids throwing codes.
I have a V1 Ti Aerie I4 exhaust. The valve arrangement is actually designed to match the OEM Valve’s open/closed positioning, but it still threw codes. Only the recalibration resolved it, no problem since. I also have their sports cat.

The V2 titanium exhaust system for the i4 and V6 has addressed the valve issues with a newly designed valve.

 

[F1 SML8R]

Quick update, my dealer ran the calibration while it was in for an oil change and all good (no more engine lights). He said basically the tolerances on the exhaust flap module are really tight. So, he's not surprised that it needed a calibration. He's done several apparently. Also, a few software updates.

Lastly, I went to a dealer that was about 80 miles away. So, after about another 160 miles of touring mode to burn in the exhaust packing, it sounds a bit "growlier" (is that a word???). I suspect like other exhausts, it'll be fully burned in after 300-500 miles. A big thanks to @Aerie for putting out a quality product. The tech said he hadn't seen the i4 version of any of the after-market exhausts (he's done a few v6's) and thought the titanium heat patina that was forming looked cool.

 

[F1 SML8R]

Ok, besides having to now have the valve calibrated that @lynchy73 and others have mentioned, it’s important to note that doing this on quickjacks, is a pain. I would say if you have access to a lift, use it!

First obstacle, the OE i4 exhaust is big and has an additional mounting bracket dead center. See pic…View attachment 63324
Next problem, the OE decat pipe (no third cat on i4) has a spot weld that unfortunately goes through the pipe making it essentially un-removeable. See pic…
View attachment 63325
Now next problem, because we couldn’t remove the decat, we couldn't squeeze the exhaust out. So after an hour of twisting and turning, I made the call. Reciprocating saw! See pic…
View attachment 63326
After that, getting it out was a cinch! Oh yeah, I skipped one other big headache, the V band clamp around the down pipe and decat. Getting that off was super hard because of the placement of the bolt. I don’t know how many extensions, elbows, etc. we used, but we finally broke it loose.

All in all, it was cool we did it, but it was a pain. BTW, you if you watch the cool install video on one of the other threads for the GRP titanium v6 exhaust install, it seems straight forward. However just know that the i4 is at another level of complexity if you don’t have a lift, the V band clamp on the down pipe to decat connection access, the spot weld that went too far on the decat preventing its removal, and finally the center bracket that got in the way of removal because the OE box is so big.

Lastly, as a reminder I got the v2 and it is beautiful(see pics earlier in this thread), even more so after a little blood (knuckles were busted), sweat and ok maybe one tear of joy when done!

I felt compelled to give an update on this for any other i4 exhaust DIY'ers. As you saw from above, my buddy and I really struggled getting clean access to the V clamp for proper placement and tightening when we did this over a month ago. The details are above.

Fast forward to last weekend and almost 600 miles later, I blew the mid-pipe that connects to the down pipe off under full throttle on the track (Buttonwillow's "The Circuit") at the end of one session.

To be clear, this was "TOTAL USER ERROR" at install. In the photo below (see red outline of the original clamp mark at an angle and not cleanly going evenly all the way around), you'll see that because we struggled to even get to it from under the car with the diffuser off, we clearly didn't fully seat the mid-pipe onto the downpipe, before torquing down the clamp.

End result of the blow-out was this:

For anyone wondering of course Lotus has no diffusers in NA (They said it would be over a month's wait). So, @GRP to the rescue with a raw carbon diffuser (thanks again Greg for the super prompt service and shipping!):

It really is a raw carbon piece. So, I spent another few bucks (and hours in labor) on high-temp radiant heat matting and metallic tape to heat protect this beautiful piece and transfer over the support bar and aluminum cooling vent for the valve controller:

In the end, this could have been a thousand times worse. So, I'm considering myself a bit lucky on this one (just more labor, clean-up and a diffuser). I'll close with the following tip again only for i4 owners given the v6 install is a cake walk compared to the turbo.

For the i4, I would recommend you also remove the lower engine bay cover in addition to the diffuser. This gives you much cleaner access to the "dreaded V clamp." Also, on the new mid-pipe, make sure you place dash marks about 8-10mm from the edge of the lip all the way around with a sharpie. This will serve as a visual point of reference when you are under the car and slipping the V clamp over the mounting lip to ensure it's evenly clamping all the way around and not tilted (I did this the second time when I re-mounted it to ensure this SHIT doesn't happen again!).

Lastly, if you look at the pic with the red outline, you'll see the thin edge that blew, was in fact covered by maybe 1mm of the v clamp. The fact that this held for roughly 600 miles before blowing off was crazy in itself. Like everyone else, we test drove the car right after the original install and that's why we didn't catch this as all seemed fine (except for the needed calibration). In any case, my choke, will hopefully prevent anyone else from making a similar mistake.

In the end, I'll chalk this one up to a learning experience and I got a cool CF diffuser out of it.