RaceGass,
I came up with 1.44".

"Larry tells us the stock head pipe is actually the same unit as used on Kawasaki's KLX 250. It has abrupt internal welds and its inlet face does not mate well with the exhaust port." Do you mean KLX300 stock head pipe?

 

Brand new from Dillon Brothers
1-800-964-1882 or 402-556-3333

 

Hey thanks for the measurement.

To answer the question : Does it have more snap?

With stock gearing it is alot better. I wouldn't say pop a wheelie snap but its alot stronger. Where I feel its strongest is in the mid to top end. After mods we are capable of 91 mph on the digital dash. Need to try the tm33 mikuni carb next.

 

Cool thanks.

 

Would the 300 OEM exhaust and header match the performance of just a slip-on from say 2 bros, fmf, or big gun?

 

The 300 pipe will be an improvement over stock. Still weighs way more than a Two Brothers or Big Gun.