Okay well I want to put a dual exhaust system on my Caprice, and I have a similar thread on another forum, but I'm going to layout the parts I have in mind. A Flow-tech Universal X-Pipe Kit(Holley Performance Products X-Pipe Kit*53622FLT), a pair of Flow-tech Raptor mufflers(Holley Performance Products Raptor Turbo Performance Muffler*50051FLT), and a set of Flow-tech Full-length headers(Holley Performance Products Standard Headers*11104FLT). I'm also going to put new cats and some tail pipe, but nothing special there. In my other thread it was brought to my attention that while running this set-up may give me a horsepower gain, it will hurt my lower end torque. My question is WITHOUT welding can the 2.5" x-pipe fit a 2.25" muffler that will run to some 2.25" tailpipes? I was told smaller pipes would increase back pressure which would increase torque, so I'm wondering would that work to save some of my torque? So I'm basically wondering if a header with a 3" collector can bolt on to a 2.5" X-pipe, and can the X-pipe clamp onto a 2.25" muffler and will the 2.25" tail pipes and muffler clamp on to each other. I just want to know if this set up is at all possible without ruining my car or falling apart beneath me. I have alot planned for this car, but can't do anything til I figure out what I'm going to do with the exhaust. I figure make the car able to take in what it can't put out. Advice and personal experience with similar situations would be greatly appreciated.

 

with ruducers it sounds great in theory
the smaller pipes will increase pressure and give bottom while still losing top end.....your better off going with one size all the way around depends opn your motor and how strong it is....either 2.25 or 2.5 all the way

 

Well that was my next question, would the backpressure created make enough torque for it to be worth doing or should sticking with the 2.5" pipes be just as good?

 

Ok, first check out my reply to 'Flowmaster or Magnaflow' thread for more on my set-up. For now, until the stock 305 is replaced, I'm running factory 2 1/4". Originally I removed the cat, put a straight section in, no muffler, and finally dual tips put the back. Very loud when revved-up which is cool but had that crackle that is like those cheap cherry-bomb mufflers. Recently I installed a Flowmaster and wow, what a difference!! The noise level when down some obviously, but I didn't know how much torque was lost. Thinking that stock manifolds, to y-pipe, to straight/curved sections before and up-over the rear axle, and finally to a split into duals would provide enough back pressure was not so. The addition of the Flowmaster increased bottom-end significantly, the transmission shifts quicker and better, and the sound is fantastic. No more snap, crackle, pop on deceleration. You failed to mention what size engine you got. 2 1/4" is plenty for a 305 or 350. I know a guy who had headers installed on his 5.0 Mustang and ran 3" pipes off the collectors, 3" x-pipe, 3" mufflers, and 3" duals. He wasted more than a thousand dollars 'cuz the car runs like a Model-T from stop light to stop light. Also keep in mind, our box Chevys are heavy so torque is important. When I replace the engine, I'm going to do the same: headers, cross-over, high-flow mufflers (probably Flowmasters; love that sound), and duals. This can all be done with clamps, reducers, and hangers on your own without welding. The tricky part is up and over the axle, which an exhaust shop can help with so with some effort and not a lot of cash, you can have that Caprice sounding and looking good!!

 

Well I have a 305 thats stock at the moment, but I plan on doing a fair amount to it. Replacing the carb, intake manifold, distributor and wires, fuel pump, put a short ram intake on it, and a bit more. Would the 2 1/2" pipes be to big you think? I was thinking that the 2 1/4" pipes after the 2 1/2" x pipe would make up for the torque that would be lost. I'd run the 2.5 straight through if it won't stop the car from moving, I'd consider changing the rear gears to replace the torque if necessary.