i did the ressy delete with straight pipes (no X) and couldnt be happier. really wakes up the sound without being obnoxious...

 

Mufflers still in place?

 

On mine? Yes...

 

Here is dyno proof now quit arguing about it its not that hard to look this stuff up on dynos
https://www.dailymotion.com/video/x5s8nr8

 

Horsepower is just how fast torque is made.....torque is what pushes you back in the seat when you push the hammer down...... sacrificing torque at low and medium revs (when street cars spend 99 % of their time there) to gain a few largely unusable horses at the top end is a joke to me. Sure LeMans and F1 cars do use straight pipes......but they also have lots of gears and are at screaming revs most of the time.....low and midrange power loss will not be a problem to Lewis Hamilton!......but would be something I would not want driving into town! A little back pressure at low revs (with either a muffler or an X pipe) will help hold the unburnt fuel in the cylinders on valve overlap so as you don't lose so much of that low down torque.....just what you want on a street car. Sure a straight tube from cylinder head to tail pipe will give you the intimate horsepower......but make it VERY loud and give you a car with nowhere near flexibility a street driven car needs. I use close to straight pipes on my track day bikes....as it rarely drops below 8k revs on the circuit.....It would not make a nice street bike though......just my 2 pence worth!