[weinerbarn]

TLDR ... Skip to results if that's all you care about.

So I finally got a chance to install my Evolution Racewerks Secondary Cat Delete I purchased from r33_RGSport. Overall wasn't too bad to do in the home garage using nothing more than a floor jack and some solid jack stands. I took it apart a couple of weeks ago and made the mistake of assuming not only that my local dealer(s) would stock the replacement catalyst to exhaust gaskets (Pre-Converter Seal), but the other issue was that I ordered the P/N listed on the Evolution Racewerks installation guide which was wrong. The correct P/N for current Gen M5/F95 is 18327856835. The P/N listed on the guide is for older generation M5, not 2018+.

I may put together a revised guide but here's the general summary if you are only doing secondary cat delete and not primary cat delete. You can reference the install guide for general instructions and tools required. Grab a bunch of ziplock bags and marker to organize your bolts.

1. Start at the top with car on ground, Remove the plastic engine cover, upper mount and intercooler reservoir. (Steps 8-10). There are (2) Torx 30 holding upper mount to engine and (1) 8mm under intercooler reservoir. There are clips on the upper mount for a wiring harness. Remove these and set the mount aside. Your forearms will thank you and you'll save some skin. You do not need to remove the O2 sensors, heat shielding or anything else.
2. Use a 10mm 12 point ratchet wrench to remove the bolts on the V band clamps holding the downpipes to the primary cats. Spread the clamps to release and allow the pipe to separate a bit.
3. Lift the car and place on a stable platform like trustworthy jack stands or ramps.
4. Remove the rear exhaust. The guide says it's optional (Step 6) but it's really just going to frustrate you if it's left in place. There are 2 band clamps up front connecting to the downpipes and 4 bolts/nuts for the hangers. There are 2 hangers just behind the rear wheels and 2 back by the tailpipes. Once these are removed, it's much easier to slide the exhaust back and the suspension supports hold it off the ground. It can hang there.
5. Remove the skid plate. The plastic belly pan is probably optional. (Steps 3-5) There are (3) 8mm screws that hold some plastic covers over the rear of the skid plate on each side. Easier to remove these and not fight with the skid plate.
6. There are (2) nuts on each pipe holding it to the engine via bracket. Once these are removed, you should be able to lower the downpipes out with a bit of a twisting motion.

Installation is reverse order. I recommend pushing the pipe up into the cat first and the sort of muscling it onto the brackets. The cat has step/ring in the center and if you don't get it lined up before sliding the pipes back onto the brackets, it's almost impossible to maneuver the flex pipe into place afterward. Loosely tighten the band clamps just enough to get a bite with the bolt threads. I used some pliers and vise grips to squeeze the clamp ears while I started the bolt. Do not tighten it now. You will need to twist the pipes a bit later to line up with the rear exhaust.

Results:

I didn't notice a significant increase in overall volume but then again, I had been w/o the vehicle for 2 weeks waiting on parts. It's not obnoxious and there's no drone that I noticed. The one benefit I picked up is the upshift "crackle" is more pronounced which was a welcome enhancement. It even brought a smile to my 15 yr old daughter's face. Take it for a 10 mile drive and be prepared for some stink as the exhaust burns off oils from manufacturing. It's going to smell like you're cleaning the oven.

End result is I think it was worth it.

[mike@x-ph.com]

Thank you for sharing

[r33_RGSport]

Originally Posted by weinerbarn

TLDR ... Skip to results if that's all you care about.

So I finally got a chance to install my Evolution Racewerks Secondary Cat Delete I purchased from r33_RGSport. Overall wasn't too bad to do in the home garage using nothing more than a floor jack and some solid jack stands. I took it apart a couple of weeks ago and made the mistake of assuming not only that my local dealer(s) would stock the replacement catalyst to exhaust gaskets (Pre-Converter Seal), but the other issue was that I ordered the P/N listed on the Evolution Racewerks installation guide which was wrong. The correct P/N for current Gen M5/F95 is 18327856835. The P/N listed on the guide is for older generation M5, not 2018+.

I may put together a revised guide but here's the general summary if you are only doing secondary cat delete and not primary cat delete. You can reference the install guide for general instructions and tools required. Grab a bunch of ziplock bags and marker to organize your bolts.

1. Start at the top with car on ground, Remove the plastic engine cover, upper mount and intercooler reservoir. (Steps 8-10). There are (2) Torx 30 holding upper mount to engine and (1) 8mm under intercooler reservoir. There are clips on the upper mount for a wiring harness. Remove these and set the mount aside. Your forearms will thank you and you'll save some skin. You do not need to remove the O2 sensors, heat shielding or anything else.
2. Use a 10mm 12 point ratchet wrench to remove the bolts on the V band clamps holding the downpipes to the primary cats. Spread the clamps to release and allow the pipe to separate a bit.
3. Lift the car and place on a stable platform like trustworthy jack stands or ramps.
4. Remove the rear exhaust. The guide says it's optional (Step 6) but it's really just going to frustrate you if it's left in place. There are 2 band clamps up front connecting to the downpipes and 4 bolts/nuts for the hangers. There are 2 hangers just behind the rear wheels and 2 back by the tailpipes. Once these are removed, it's much easier to slide the exhaust back and the suspension supports hold it off the ground. It can hang there.
5. Remove the skid plate. The plastic belly pan is probably optional. (Steps 3-5) There are (3) 8mm screws that hold some plastic covers over the rear of the skid plate on each side. Easier to remove these and not fight with the skid plate.
6. There are (2) nuts on each pipe holding it to the engine via bracket. Once these are removed, you should be able to lower the downpipes out with a bit of a twisting motion.

Installation is reverse order. I recommend pushing the pipe up into the cat first and the sort of muscling it onto the brackets. The cat has step/ring in the center and if you don't get it lined up before sliding the pipes back onto the brackets, it's almost impossible to maneuver the flex pipe into place afterward. Loosely tighten the band clamps just enough to get a bite with the bolt threads. I used some pliers and vise grips to squeeze the clamp ears while I started the bolt. Do not tighten it now. You will need to twist the pipes a bit later to line up with the rear exhaust.

Results:

I didn't notice a significant increase in overall volume but then again, I had been w/o the vehicle for 2 weeks waiting on parts. It's not obnoxious and there's no drone that I noticed. The one benefit I picked up is the upshift "crackle" is more pronounced which was a welcome enhancement. It even brought a smile to my 15 yr old daughter's face. Take it for a 10 mile drive and be prepared for some stink as the exhaust burns off oils from manufacturing. It's going to smell like you're cleaning the oven.

End result is I think it was worth it.

Thank you for your business. Glad that you like it.

[cailas]

Maybe someone did secondary dp’s and x pipe?