Thread: exhaust size for 500whp

all the 3" housing are longer to give the transition to the 3" outlet look at the t31 housing is is a 4 bolt 2.5" housing then look at the gt 4 bolt 3" it is just tappered out to 3inch after the turbine outlet it is still 2.5" at the turbine , the larger housings just look to have a progresive transition from the turbine wheel to the the actual out let where the down pipe hooks up

looks like Ill be going with a 3 in full exhaust. Does anyone know for a fact whether or not the 4 bolt patterns on the garrett turbos and precision turbos are the same?

i think 3'' will suit your needs very well. if you have to order offline if you cant find any cheap in your area. would probably be your best bet

If im reading this flow calculator correctly (Compressible air flow calculation)

2" exhaust can flow (1atm, 60F, 15ft length pipe) 289 CFM
2.5" (all things equal) 446 CFM
3" (ditto) 681 CFM

(this also assumes pipe is smooth inside and straight - start to end)