Ii finally did my ISR. its really good. i used a plumbers cap and stuffed it into the hole where the lower silencer was and put a clamp on it. it really struts its stuff when you hit 4,000rpm. thats when the sound is perfect. i suggest this mod to everyone who owns a taco.
Cap - 90 cents
Paint - 99 cents
ok, to be more specific (pics are not mine):
In the following pic u can see a J-shapped "tube". this is the silencer.
To plug this silencer, head on over the local home depot and grab a few different sized plugs. I purchases 2 and had one just too big and just too small. So, after removing the stock silencer and its clamp, i took the smaller plug (spray-painted black) and put it into the hole that was originally occupied by the silencer. Finally, i adjusted the plug the way i wanted and took an automotive-style clamp (with a thumb-twist, to make life easier) and tightened it until no play was found with the cap. Thats it!!! all there is to it! thats why i suggest it. And for the more daring folks, there is an upper silencer, see 2nd pic, that has a line running to the gas tank. I personally didnt do it because i would prefer not to ruin my truck. Plug this the same way, but your either going to have to create a plug with a nipple or t-fit it into another line running into the intake. the result is that (with the lower tube removed) i found that around 4,000rpm, the sound was spectacular. it didnt have the wail of a ricer and the depth of a V8, it made a sound all its own. i think its AWSOME. everyone should do this mod. It even makes the truck idle a tad deeper i think.