So, what would be the recommended diameter for A12, A14 & A15? ( assuming u r running a complete lenght exhaust system with 1 straight flow muffler at the tail pipe end )

i would reccomend using a ressy aswell as a cannon muffler.

im using 2.5" with cannon and ressy and its loud and will only be good for yop end power.

2" is more that good if u want a nice street car noise

Errmm...and on which engine cc would your suggestion be applicable?

i would suggest 2 inch up to 1.8lt engines unless there turboed i wouldnt go 2.5

my worked over a12 is running a 2" system with a high flow muffler (turbo muffler they call it). Seems to suit it fine, loud enough, and seems to let it breathe just fine. Its not mandrel bent, so the bends are probally only 1 3/4".

But for the drag car, that paint on the pipe trick is not as strange as you think. My brother also used it on his supermod (speedway car), and I have heard it before as a poor mans method for pipe length. It works good enough that spending dollars on a pro to work it out, only to find that he cuts it at the same place, a waste of time.

thanks guys
thats great info

gentlemen,
imn full of questions this week

40mm suideraughts on an a worked drag a14 normally aspirated motor
what would u guys recomend the size of the ram tubes should be
is there any calculation to get the correct size or is it just trial and error
thanks

Generally trial and error minnesh, the shorter the tube the more top end it will give, longer more torquer, just like longer runners on forklift inlet manifolds give more torque.

ok this is for the ram tubes that fit in front of the carbs
and not the headers that fit on the head
is this correct
thanks

Correct!