Hi Guys,

Putting a new exhaust on my A15 in a few weeks. I'm planning on going with a 2.5" system, a few people have reccomended this already, and I have seen some people with worked A12's even getting good results.

Some very basic specs on the motor:
A15 +1mm o/s approx 10.2:1 comp
Twin 40mm sidedraft dellortos 32mm chokes H89 Ported oval port head & JTS GX manifold
Wade 140 grind cam (40/70 ish)
JTS 4:2:1 extractors with long secondarys
Currently running a 2" system with one large baffled non- straight through muffler.

The problem I have is it starts to lose power around 6700 when the cam should keep going to around 8000.

Thinking of going to the 2.5" system with a nice straight through muffler and a resonator.

Does anyone have any real- world experience in going to a 2.5" system on an a series?

I'm looking for comments on the loss of bottom end and gain in top end that the 2.5" system would give me?

Cheers

Matt