Hey guys. I am piecing together a turbo kit. I will be using a garrett t3/t4 57 trim .63 a/r turbo. What is the difference between the 4 and 5 bolt. The 5 bolt seems to be a little more money. Is it better performance? fitment? Spool? anything?

Thansk

 

no it just takes a different exhaust flange on your downpipe thats all. the 5 bolts were designed so that a flapper housing can bolt on and use an internal gate if you choose to do so.

 

5 bolt housings are generally larger overall.
the 4 bolt housings have a smaller footprint

4-bolt is to be used with an external wastegate
5-bolt has the option of using an interal flapper if the housing was cast with the flapper hole

 

I've also heard that the 4 bolts will flow better because there is less restriction with the flapper hole in the turbine housing. Now it might just be a small amount, but any little bit helps. I always use 4 bolt.

 

eh, probably but its very very minimal.
my 5 bolt housing is sans wg hole