I'm seriously considering doing the topic reversion, depending...

Although I like the function of the B&M SSK installed on mine when new, IMO the "downsides" (literally) offset the upside. In my sig topic, I've outlined my attempts at achieving a quieter exhaust, i.e., utilizing a Milltek resonator pipe in combo with aftermarket header and Milltek cat-back system. The "downside" of the B&M (as well as Alta and Cravenspeed) is the extended shifter box that hangs down into the space the top radius of a resonator can would otherwise occupy. I've viewed several DIY install videos which all show alteration of the main aluminum heatshield above that area, as well as various home-brew methods of sealing the shifter box enclosure from dust or water intrusion. B&M SSK (as mine does) included an aluminum bottom panel which addresses that last issue. Two days ago, I attempted to install a replacement heatshield ($50 from OEM MINI parts dealer), however concluded that must be modified in the same way mine was in 2006, so I reinstalled the modded one again while removing Hushmat adhesive-backed foam insulation with concerns about water absorption which could promote rust long term as well as discourage "hitchhikers" like the one shown below. Doing so resulted in same resonance vibes at ~ 3000rpms I had (mostly) eliminated with the Hushmat.

So as stated, now I'm considering buying a used OEM shifter actuator, then pulling the B&M shifter out and rebuilding it with combo of OEM actuator and B&M solid mounting bushings already in place. My thinking is that would accomplish; restoring OEM clearance beneath the shifter box, utilization of the replacement heatshield plus adequate clearance for Milltek's res-pipe canister. Some might say that's going backwards, however the solid vs OEM rubber bushings alone should improve shifting response (although not decrease throw). What is not known at this point is how B&M's extended box was attached to the OEM shifter box, i.e., loosely sandwiched or glued (not outlined in Pelican's install article here (noting that was pre-FL version with the white housing) and whether the B&M shifter cover could be reused in combo with shorter metric attachment screws to the chassis.

Seems doubtful anyone active here has ever done this but figured I post a new topic rather than add it onto mine. TIA...

Cross link to ad: WTB: R52/R53 6-speed manual shifter p/n 25-11-7-548-282 (2005-2008)

 

I came up with an alternate method for modding my bottom box...

...in this goofy thread:

https://www.northamericanmotoring.co...-tube-mod.html

Was included a few pics of my Cravenspeed shortshifter install, at that time I had decided to run "naked" with no lid as I had read that many people just left them off and didn't seem like too big a deal, but what I discovered was a side-effect of intolerable heat that I could not abide --- perhaps no problem for colder climates, but for me down south in the hot summer I just couldn't stand it.

I neglected to update the thread and neglected to take any pics, but my solution worked out well because it keeps the heat out.

What I decided to do was make a "soft box" using DEI Reflect-a-Cool:



Basically emulating the NM extender for R56,
but utilizing the DEI stuff to form the "box".



So I cut a the big square out on the lid and formed what would be best described as a "pouch" because of course it wasn't exactly squared, the DEI stuff worked excellent for this purpose as the adhesive is very strong and stuck very well, and then doubled up by adding another layer for the inner portion so it was nicely smooth non-sticky on the inside.

Cut my lid the same as this guy did in his video, except instead of fabricating a metal extension,
I went with the heat shield fabric.

 

OBS -
I did fully read your linked topic and commented a time or two. Similar to my own situation, your combo then of header and no resonator resulted in too loud inside the cabin. Further, root cause of resonance vibes ~ 3k rpms. I do like Milltek products and prefer to resolve my SSK clearance problems without resorting to cutting up the new replacement heatshield. The adhesive backed Hushmat foam insulation I used (removed now) was part of a leftover roll used on my Can-Am side-by-side. Their tech specs claim water absorption: 1.6% or less, which I dispute. Once wet, it's like a sponge retaining that moisture far too long for where I installed it. Also, attraction by rodents is a factor not considered. I did some searches for adhesive backed heat insulation on Summit Racing's website and saw the DEI products (reviewers stated "Chinesium") and also found this product stated as Made in USA by Maier which looks promising being adhesive backed aluminized fiberglass (other sizes available). I wrote them last night asking to confirm whether USA content or simply cut to size from imported sheet stock and about adhesive strength for my application. My thought is to apply that to same areas as the Hushmat foam above the heatshield to avoid metal-on-metal vibes but with no apparent downsides (other than cost).

I also viewed the linked Cravenspeed SSK install video which was very comprehensive. OTOH, he seemed surprised when discovering the heatshield must be modded to accommodate the extended length of SSK in short shift actuator position (21 mins in) and just 1/8" final clearance to the top of his JCW resonator (22 mins in) - exactly what I want to avoid!. I briefly considering buying a Cravenspeed SSK left in the OEM-equivalent position, thus not necessitating the extended box mod. Rather than doing that, I figured more practical as outlined in post #1 with an OEM actuator lever or replace the entire shifter assembly and sell my complete modded shifter to recoup costs. In the end, performance mods almost always have offsetting compromises. I've fooled with mine more than long enough and want permanent (and quieter) resolution.

 

Update:

Determined that WMW has a shift actuator lever (only), but decided to proceed with the complete unmodified facelift shifter assy from ALLMAG, which is from a 2005 R52 donor with 56k chassis miles. Price on ALLMAG website and on their eBay store was relatively high but I contacted them asking for price reduction, got that plus avoided Arizona sales tax mandatorily collected by eBay. Condition should be reusable as-is, although I have to open the box cover to attach my shift cables anyway, so will inspect the joints for free play, plastic bushings/retainers for wear, lube thoroughly and likely order WMW's more durable $60 machined plastic bushing kit. All that should result in OEM new (or better) functionality while resolving objectives outlined in post #1. Further, removing my original shifter assy with 6.8k total miles at this point and leaving the B&M SSK now installed intact for subsequent sale on NAM as a turnkey assy will help recoup a significant portion of parts costs. Also ordered another Milltek MSM311 resonator pipe, so the non-res pipe now installed will go on the block same time. Further updates on my sig topic after all that is done, hopefully in a few weeks from now.

Edits - I did order WMW's bushing kit and 12"x24" sheet of the DEI "Reflect-A-Cool" adhesive backed insulation as suggested by OBS (which will be applied to any OEM heatshielding which overlaps or where metal-to-metal contact promotes resonance vibrations).