my second muffler in my 89 240 (the one thats one up from the main muffler) has a couple decent sized holes in it. I am unsure how much this is affecting my performance and also unsure what to do about it. should i patch it up? or possibly buy a new part? or maybe just go big and get an entire new exhaust system for my car. also the car rattles at low rpm (idle); could this be the muffler/exhaust as well?

One of the easiest and best upgrades you can do to the 240 is get a new exhaust. The factory exhaust system is very restricitve and definetly gives less performance compared to an aftermarket exhaust.

about how many horses would i expect from new exhuast? just catback say? also taking into account the fact that i have holes in my muffler right now

i think over the stock exhaust on a ka24de a good exhaust will give about 5-7 hp, nothing crazy somewhere in that range. u should notice about a 10hp difference since u are losing over stock right now.

..and catback is the preferred exhaust, its def better than stock and better than axle back.

Ok thanks. Would it be much use to get a new manifold as well? like is it worth the work and money? and also how difficult is it to install catback exhaust? should i be getting a professional to do it or is it a good D.I.Y. candidate?

well unless u go turbo, u dont have a manifold. im assuming u mean header.

obviously an aftermarket header will give performance increase. anything that helps the car breathe better is gonna make a performance increase: intake/header/exhaust

i think a good header will give about 3-5 hp. i think last i heard hot shot has the best dyno proven header (not carb legal, i live in cali so i know). I think headers are a lot more work to install but most give instructions on how to install, if not check the web, someone has a header install diagram.

Is it worth the money? Well thats up to u. Ur gonna pay about 300-500 on the header and so ur looking at about 100/hp and thats about right for bolt ons. (For comparison, an intake cost about 200 for about 3-4 so thats about 50/hp)

Exhaust install is fairly easy if u have a jack and four stands. should take u about1-2 hours if ur not used to doing it.

sounds good. well thanx alot im gonna look more into it next month. happy holidays.