Standard road spec rods are manufactured to withstand generally 20m/s piston speed. ( Think the piston has to go up ,stop dead and then come back down, stop dead and then go up again etc). This causes a lot of stress. When you start turning the boost up and putting more pressure on the piston crown your increasing the speed of the pistons Meter/second up and down the cylinder bore and also the general combustion chamber temperature ( Ex gas temp close to 1100 deg c) if your upping the rev limit or moving the power curve further up the rev range then deffinetly use forged rods and fastners. Race application rods ( scat etc ) generally withstand 25 M/S MAX! The 1st failure point usually is not the rods themselves but the standard fastners in the big end, hense why people use forged rods along with ARP 2000 fastners( or similar brands )if you put too much stress on standard rods they will stretch and fail. So if your uping the boost and incresing the stresses on the engine and piston/rod setup then yes you deffinetly need forged rods and uprated fastners. Forged pistons are used due to the harder outer coating the forging process creates this is purely due to the higher temperatures created by more pressure/power. Hope this helps , and i am using scat rods and they seem fine matey