I INSTALLED McCORD'S ON MY 96 XR 400 AND IT MADE A WORLD OF DIFFERENCE ,MUCH BETTER THROTTLE RESPONSE,STARTS EASIER,AND DOSEN'T STALL AS EASY,THE GUY I SPOKE TO(RON I BELIEVE) THERE OWNS THE COMPANY ,HE WOULD BUILD THE SYSTEM AFTER HIS DAY TIME JOB,FROM WHAT I UNDERSTOOD THE WAY THE SYSTEM WORKS IS THAT ONCE THE ENGINE IS AT A GOOD RPM AND YOU CHOP THE THROTTLE ,THE SYSTEM GIVES YOU MORE INTAKE VOLUME,SO WHEN YOU OPEN THE THROTTLE IT DOESN'T TAKE THAT EXTRA TIME TO BUILD UP INTAKE PRESSURE TO SUCK THE FUEL FROM CARB,I ALSO OWN A 00 KTM 400 EXC WITH A PUMPER CARB AND THE XR HAS A BETTER LOW END RESPONSE THAN THE KTM,SO I THINK THAT YOU WOULD GET MORE BANG FOR YOUR BUCK WITH THE PCIS THAN THE PUMPER CARB,THE ONLY DRAW BACK IS THAT YOU NEED TO BE A LITTLE HANDY WITH A DREMEL TOOL SO THAT YOU CAN MODIFY THE THE CARB,HE'LL TELL YOU TO SHAVE OFF THE END OF THE CARB THROAT BUT I FOUND IT WAS EASIER TO SHAVE THE INSIDE OF THE INTAKE BOOT WITH A UTILITY KNIFE,HE ADVERTISES IN THE BACK OF MOST DIRTBIKE MAGAZINES,HIS NUMBER IS 406-248-5595 AND THE PRICE IS ABOUT 190 BUCKS