nofreetime - Try going on ebay and look at the folks that sell your car and they may be able to get the parts for you. I know that Pro-RC is supposed to be in the US but I don't know if they stock parts. There's some connection between himotoracing, pro-rc, import-houses, that I haven't been able to figure out. Anyway that's the only other part stocking company I know of at this point.
The only other thing is if you have the 1/8th scale they are supposed to be modeled after the kyosho 7.5 - but I don't know how accurate that is/how well parts exchange. I'm planning on taking it up to a LHS about 15miles from here to see how transferrable they are.
OzHole- I found 2 topics on it one here
[link=http://hpieurope.custhelp.com/cgi-bin/hpieurope.cfg/php/enduser/std_adp.php?p_sid=I6nJUtZh&p_lva=&p_faqid=451&p_created=1081518194&p_sp=cF9zcmNoPTEmcF9ncmlkc29ydD0mcF9yb3dfY250PTImc F9zZWFyY2hfdGV4dD1ib2lsJnBfcHJvZF9sdmwxPX5hbnl_JnB fcHJvZF9sdmwyPX5hbnl_JnBfcGFnZT0x&p_li=]HPI Site[/link]
...and one here
http://www.ofna.com/faq.html
They both give different directions but OFNA even says that this will not stop all problems (So I guess you have problems like with with the big names big dollar brands). Have you owned other nitro vechicles? If so does it seem worse than the others?
The Himoto's are the same as the Redcats. The Redcats might send the bigger engines with a polished pipe though and maybe a couple things like that but overall the same thing.