I just bought an S4 motor to put in my sandrail and it's missing the exhaust sleeves. I already have 2 1/2 inch exhaust and would just need to enlarge the holes on the RB flange to have matching exhaust for the ports. At the dunes I'm normally at 3500 rpms and above (5-7k regularly) would I be ok running it like that and would I loose any power doing so? I've read up on it on here but everything only accounts for driving a car on the streets and the loss of low end power (which I don't really use), is there any other downside to running it like this?

 

From feedback I've gotten from others I can weld some tubing on the flange that will act as a sleeve and that should help my flow. I'm wondering how far in it should go, and what diameter would help me make the most power (if anyone has tried this and had success I'd appreciate some feedback before I do anything I'll have to undo)?

 

easiest method would be to tig weld some stock sleeves to your manifold.