What kind of o-rings works best on Q pipe V1 flange? Did a search but cant find any thing,must have been on the old site.

Thanks.Thats what I needed to know.

I called SCP and asked Matt for the part number of the o-rings a couple weeks ago. He said he never uses o-rings. He recommended putting a nice bead of red rtv around the ID of the pipe's flange before sliding it on the engine flange.  I'm going to try that this fall.  Ultra gray and o-rings on my v2 failed miserably and trashed the front of my engine while we were in glamis last year...

Q gave me the following part number for the V2 pipe but never would send one for the V1. He did say the V2 ring would not work for the V1 pipe...
McMaster Carr V2 o-ring part number 9396K112

Go here:
http://www.mcmaster.com/#viton-fluoroelastomer-o-rings/=nqvqcf

Select: Viton® Fluoroelastomer O-Rings

Pick your poision

I have a ton of Viton Orings that fit the Qpipe in my garage.

Viton is oil and fuel resistant I believe. The rubber orings get "hard".

The Viton® fluoroelastomer resists chemicals and oil. Temperature range is -15° to +400° F. Durometer hardness is A75. Meets ASTM D2000/SAE J200. Color is black. vs: Silicone has good resistance to low and high temperatures. Temperature range is -65° to +425° F. Durometer hardness is A70. FDA compliant. Color is red-orange
The Silicone for me lasted longer when I had the Q pipes vs the Vitron

Myself, I'm working on precision metal slip joint on the next batch of pipes, might die cut a flat silicone gasket to match, so no leaks what so ever.

Mitch, have you thought about trying an exhaust ball joint instead?
The two parts are held together by spring pressure, and they seal quite well.
Best part is that they can be adjusted for slightly different frames by hand, which could have eliminated some of the problems with Q pipes and AAEN pipes fitting up to other frames.
One of the problems with any type of straight slip fit joint is that any side load (torque, vibration, poor fitting pipe, etc.) will cause a gap for the exhaust and oil to shoot through back onto the engine, whereas a ball joint would just rotate and maintain a seal.

I've been thinking about converting a pipe just to test out the concept, I'm tired of using O-rings and silicone.

The trick with a ball joint is to have the inside ball coming from the engine and the socket going to the rest of the exhaust, that way the ball will expand from higher temps and seal tightly against the socket.
I guess the only problem really is that the small chamber it creates might change the tuning of the pipe itself...which could be remedied if you were building pipes, obviously.
This is about the closest picture I could find of the type of ball joint I have in mind, they're on nearly every piston engine aircraft flying today.