been looking at the next step for tuning my cossie and i have no idea what the difference is between the two (other than the colour).
the car they are going into is a 93 escort cosworth has low comp etc so which ones shall i fit?

 

Light blues (400's) good for a solid 380-390bhp; 410-ish bhp max at a push.

Greys (403's) good for 440 ish max. Dependant on turbo, headwork, fuel pressure and other factors etc.

 

no difference, only the colour

 

...and part number, and flow rate, and....