Intermeccanicas with tube frames have more room in the rear because of the forward placement of the engine which allows wider rims/tires.
But they're a b!tch to install a Berg-5 in...
I know that Henry(IM) makes further adjustments to the frame on an IM6 which probably facilitates the 5 speed(915)/flat six engine install...whether that applies to a BERG5 is beyond my understanding but could be part of the explanation(?)
Totally different animal.
Intermeccanica can do just about anything a guy could ask for:
VW 4-speed with a VW flat 4 (Type 1 or Type 4)
- 901 with a VW flat 4 (Type 1 or Type 4)
- 915 with a VW flat 4 (Type 1 or Type 4)
- VW 4 speed with a Subaru 4-cyl
- 915 with a Subaru 4-cyl
- Subaru 5-speed with a Subaru 4-cyl
915 with a Porsche 6-cyl
- Front ends are available with:
- VW torsion bar and ball-joint suspension, brakes, and steering box
- VW torsion bar and ball-joint suspension and brakes with a Golf rack and pinion
- 914 suspension, brakes, and rack and pinion
- 911 suspension, brakes, and rack and pinion
Converting from one set-up to another ranges in difficulty from "pretty easy" to "please just build a new car".
For example, getting from a 914 front suspension/brakes to a 911 set-up is just parts and labor. Getting from a VW beam front suspension/brakes to a 911 set-up means cutting off the front half of the car (or just starting over, more realistically).
A 5-speed after the fact is another, really rough proposition. Once the car is set up for a VW 4-speed, getting to a 5-er is no easy task. I spoke with Anthony about it this summer, and what he described was a very, very (VERY) labor intensive reconstruction of the back half of the car.