Does the Ultrathrust muffler perform as well as a tuned pipe for speed? I'll be running an Irvine .53.

NO.

They lack a few RPM vs a tuned pipe, but they do not have the quirks that a tuned pipe has.

Vince

Okay...answer a little too short. If you tune the pipe right, you'll get more out of it.

Yeah that's it....what he said

The pipe will be more difficult to set up and tune, it wll be more sensitive to peaking as it "comes on" the pipe most likely with a very narrow power band and plug life wll probably be compromised. The advantage of the Ultrathrust or Jett style tuned muffler will be somewhat less RPM, better plug life, less peaky performance and a wider power band PLUS the ease of installation.

A simple homemade mousse can setup will function as well as the UT muffler, be lighter, and cheaper - especially if you already have the Mac's header pipe. There are several sites on the web showing how to build one. Let me know if you need the addy's.

Ernie

With a properly tuned pipe, just how much stronger would a 10x7 prop run than with a UT?