After upgrading from gsx600 tbs with 1.8 injectors to gsx750 tbs with 2l beige injectors I used the megasquirt req'd fuel tool. it came out at 15.6 at 14.7 to 1 AFR.
My question is why did it run like crap at 15.6 and work much better at 16.6.

Hi Bob, fuel pressure may be the culprit as the new tbs came with a fuel rail with prv. Don't have a proper fp gauge so used a footpump gauge.Is running mainly lean especially at high revs. Working through individual bins at present. Sorted upto around 3500rpm. 60 miles today in 2 hours. 3 gallons of fuel Better get it sorted for Le Mans in 3 weeks time.

We've just reduced the size of our primary injectors from 165cc/min to some that are 150cc/min that spray better and are much more consistant.

I also altered the Req fuel from the old map to the new injectors cc/min and it appears nothing like, the new smaller injectors need much more fuel on to get the car started but then when its running it would appear that it needs less as they are actually spraying more.