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Measure Twice, Cut Once: The Crucial Fabrication Stage of our E91 GTS Tribute Build
BY Mike Maravilla //
September 19, 2023
Photography: Dan Levins
  • The ambitious Pit+Paddock x Bilstein E91 M3 GTS strives to re-create the E92 M3 GTS’s magic in wagon form using a 4.6-liter stroker motor and the best of the aftermarket to do so.
  • Aside from performance metrics, it’s important that we create the truest factory-finish product possible, which means meticulous attention to detail from the onset.
  • Precision Sport Industries (PSI), our build partner, is well-suited to the task as a BMW-focused specialty shop and takes us through every tiny fabrication detail required to pull off the effort.

Lots of cars look good from ten feet away. But from the onset, the Pit+Paddock x Bilstein E91 GTS Tribute build has aspired to be more: create an E91 M3 GTS fighter that could’ve rolled off BMW’s own manufacturing line. To be microscopically true to our ambition, it’d require some serious BMW knowledge and a generous slathering of aftermarket support from well-recognized brands like AkrapovicMOTUL, StopTech, BBSCarbahnCSFEventuriFuture ClassicSPL PartsSupreme Power, and Turn 14 Distribution.

While the aftermarket parts continued to trickle in, the second part of this ambitious build required us to lean hard on our carefully selected build partner, Precision Sport Industries (PSI), to flex its seemingly infinite library of BMW intellect to source and fabricate everything we’d need under the skin. After all, the goal wasn’t just to arrive at SEMA, like so many cars do. The objective was to arrive with pomp and circumstance. And PSI took that challenge on with immense commitment.


Of course, before we could really start any of the fabrication work, we had to finish taking both cars apart. This allowed us to take stock of what parts we’d retain from each car, which parts could be refurbished, and which would require us to replace entirely. Every clip, nut, and bolt were carefully considered and taking accurate inventory of both cars was an immense undertaking.

Amidst this tedious effort, both drivetrains were removed. The S65 from the donor E90 M3 moved straight from the car and into an inconspicuous black box with a shipping label set for Carbahn on it (more on this later) while our wagon’s N52 inline-6 eagerly watched the next steps from the sidelines.


At this stage, the body might look like a straight-forward swap, but there are a ton of small differences between each car. To fit the wider M3 rear quarters and fender liner, the wagon’s inner fender area was fitted with the E90’s supporting structure. Rather than transferring the entire fender, specific sections of the M3’s quarters were chosen by PSI carefully. This allowed us to achieve the look of the M3’s wide fenders but retain important sections around the wagon’s taillight area.

With the internal supporting structure sorted, PSI moved onto grafting the E90 M3’s outer fenders atop the E91’s body. “We needed to take our time fitting the outer fenders right,” said Sean Myers of PSI. “We tack-welded the fenders to the E91’s body one at a time in order to manage heat and minimize any additional body work later on.” In total, there were hundreds of welds to consider. But the team knew that patience and care were crucial here. Sacrificing quality for the sake of speed would only set the entire build back and time wasn’t a luxury we’d have at any stage. After weeks of work, the wider M3 fenders were finally on the wagon.


The E9X M3’s rear bumper is vastly different from the standard BMW fare. Not only does it have to mate up to the wider fenders at either side, but it also must accommodate the M3’s quad exhaust and built-in diffuser. The solution for our wagon was multi-faceted. First, the underpinnings. Like the quarter panel section, the rear bumper area needed a brand-new inner structure support to mate with the wider fenders and M3 bumper.

To respect the E91’s unique shape near the taillight area, we couldn’t just fit the E90 M3’s bumper panel onto the wagon. Instead, the top of the wagon’s rear bumper was seamlessly but painstakingly conjoined with the lower half of the M3s. This allowed us to integrate the crucial design cues we mentioned earlier.

But we weren’t done yet. Since the E91’s factory exhaust piping routed out of one end, there wasn’t adequate support for the upcoming M3 unit. PSI had to go underneath the car one last time to fashion new exhaust hangers that would provide ample substructure for the replacement piece.


Bar none, this was the most time-consuming parts of the entire build process. But like I mentioned earlier, the Pit+Paddock x Bilstein E91 GTS intends to be a no-compromise, OEM tribute. Cutting corners for the sake of time is simply out of the question. But now, the pressure is on. The next stage is where the car’s GTS form will start taking shape.





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