RonMAIDEN said:
My friend works at a exhaust shop and he uses nicely soft bent pipes (paying extra for mandrel bent on a NA 4Runner is kinda silly) and you can't tell by looking and who's seeing that much of your exhaust anyway?
I got a quote for a full job for a little over $300 (standard price,a little more for SS) for new pipes and the 24" muffler and a nice tip.
I can't see spending double for a full catback that will net nothing more in performance or sound but I also don't have a deep wallet to spend extra for madrel bent pipes and a TRD logo even tho' the TRD does look good.
I can't see spending money for an exhaust system that's more restrictive than stock.
Mandrel bending has absolutely NOTHING to do with looks, and has everything to do with performance. If you are not going with mandrel bent pipes, RE-USE the stock piping, (cheaper anyway). Changing the stock pipes for crush bent aluminumized mild steel pipes is a downgrade.
"Consider a straight plastic straw that you might use to drink a soft drink. If the straw is completely straight, it's very easy to blow air through the straw, as there are no restrictions. However, lets say you decide to bend the straw 90 degrees into an "L" shape. Now, blowing air through the straw will be very difficult, as the opening at the straw's elbow will have changed from a circle to a very narrow slit. This is exactly how the pipes in your car's intake and exhaust system work. Air is drawn through pipes, which, when "compression bent," become very restrictive to the flow of air. Mandrel bending is the solution to this problem. Mandrel bending works much like the flexible straws that you can buy in a grocery store. When the straw is bent, a flexible section of the straw expands to maintain the round opening no matter how much of an angle the straw is bent at. When an exhaust or downpipe is manufactured with mandrel bends, the steel is allowed to stretch on the outside of the bend and compress on the inside of the bend, maintaining the nominal pipe diameter. Exhaust gas follows fluid dynamics. You want to eliminate backpressure while maintaining exhaust gas velocity. Mandrel bending allows the hot exhaust gases to flow with less turbulence.
Remember, all of your muffler & exhaust manufactures, all of your
car & truck magazines that do there own independent tests. And
all of the independent test that you see on the internet all show the advantages of mandrel bending over press bending.
2. Myth-You don't need mandrel bending unless you have a nascar running 800+ horsepower.
Truth-Mandrel bending alone will add 3-5% more horsepower and torque.
3. Myth-Your motor is to small for mandrel bending to make any difference.
Truth-It doesn't matter what size your motor is you will still get a
3-5% gain in horsepower & torque. Obviously the bigger the motor, and the more horsepower you have, the larger the gains."
http://www.bobsmuffler.com/muffler_myths.htm
Here's another one taken directly off superstreet.com
"Q. Hi. I was just wondering about differences in mandrel and crush bent exhaust piping because where I live, mandrel bending isn't really an option. I wanted to find out if you could use a slightly larger diameter pipe to solve the back pressure problem if I were to use the crush method on my NA SR20.
Mark
Barbados
A. Ideally, mandrel bent exhaust piping would be the way to go. Crush bent is cheesy and restricts flow at every bend. Even if you increase the piping diameter throughout, you'll still be restricted by the smallest point along the way. Fortunately, with the NA motor you could use a little bit of back pressure, but if it were up to us, we'd go mandrel bent all the way. Since you don't have access to the mandrel bending machines,
another option would be to use mandrel bent elbows and weld them in where needed when fabricating up the exhaust. You can look at a lot of the big manufacturer exhausts to steal ideas for yours. You'll notice that most of them don't follow the stock exhaust bends, but are altered to be as straight as possible from front to back."