The tubular manifolds will release a lot more power as well as sound.
Like Rich I had mine down about 18 years ago when the prices were somewhat lower.
Mine is the "crossover" system where the secondary pipes go under the sump. This gives good length on the secondaries , but it does mean that the sump oil gets pretty hot. The newer unit have a modified design where the each bank goes down the same side of the car. If I had unlimited resources I would switch to the new system tomorrow.
There are a couple of watch points
A The brake fluid reservoir needs heat protection from the number bank primary on the right side.
B If you do have the crossover system like mine , then you must switch over the lamda sensors, or they will be reading from the wrong bank of cylinders.
