DIY Chip tuning

[David Bevan]

Does anyone know of a device or gismo to plug into a UK spec'93 E36 325i OBD port, to gain access to the ignition and injection maps, so that i can backup and alter them.
I am making a supercharger setup for my Bimmer and wanted to know if i can retain the original ECU with modified maps or if i have to spend a fortune to buy an after market system like the Emerald KM3D and sacrifice some of the features of the DME unit.
Bear in mind that i don't want to spend £thousands on an interface and software if it won't do it all.

Cheers fellow Bimmer fans

Current:
93' BMW 325i Coupe, totally rebuilt engine bored to 2553cc head polished and ported, JE 10.5 to 1 CR drop forged Pistons, total seal rings, polished crank. VANOS plate spring upgrade, Cleaned Hydraulic lifters, Stainless tubular equal length headers, de cat pipe, scorpion stainless STW backbox. KNN cold air induction. Lowered and stiffened Bilstien suspension, Around poly bushes, 17 inch BMW 5 spoke alloys vredistein ultrac 225,45,17. Cross drilled and grooved discs and EBC greenstuff pads all round. silver leather interior, 18 button OBC, and most importantly a totally wax oiled body.

Future:
Bespoke Centrifugal supercharger, intercooler, Bespoke boost control system, rising rate fuel pressure regulator, secondary high pressure fuel pump. prospective 7 to 10 PSI boost and 320-360BHP (hopefully) maybe a stand alone ECU.

Past:
E30 M325i had it for a month wrote it off on the nurburgring shipped it back thanks RAC! bought a 320 SE coupe and made it a 325i coupe with a powerdyne supercharger 285Bhp very scary in an E30 2 years of great motoring. written off by a drunk driver then drove off Swine!

Nissan 200SX 1.8 turbo uprated to 260Bhp engine lasted 6 months, what a heap of C***