I just purchased a header for my 88 SE and I heard that the wit hthe stock exhaust system the noise is almost unbearable. Is this true? If it makes a big difference in noise I am also going to do a custom exhaust from the header back then. I plan to eliminate the stock catalytic converter and do a dual exhaust with 2 mufflers. The header is 2.5" so I plan to continue with 2.5" pipe then where it divides should I keep it 2.5" or go to a size smaller like 2"? Also I dont have a bender just a cutter and a welder so I need to get the pieces pre bent, what bends are needed like 4 45" bends? Should I just split the exhaust for the dual mufflers or is there a more effective method to do this? Also will I have a problem with the 5th and 6 ports? If so what will I need to do to make them open?

 

Sir, I promise that you will need (and will be happy with) an RB presilencer. I believe they are stainless steel, and I know they will solve the 6ports issue, and help reduce noise.
As for splitting it, any old y-pipe will do, but stainless is preferred, and mandrel bends are must. After the split, it is better to stay smaller than your regular pipe to maintain exit velocity. 2" would probably work if you are doing 2.5" back to the Y. Maybe a little bigger than that. As for the bends I'm not sure.

 

Well you need a cat, especially with an NA (turbo cars are quieter cause the turbo muffles some noise), otherwise the noise WILL be unbearable. 2.5'' is fine. The RB presilencer is supposedly good too, and should be quiet enough. Good luck, and the racing beat mufflers are supposedly good (have a nice sound while not being restrictive)! APEXi N1s are nice but a little to loud for me.

 

as far as the noise being unbearable and what not... mines not that loud at all. and i have a header and a high flow cat. and as far as replacing the cat. with a straight pipe go with the straight pipe and presilencer from racing beat the straight pipe has the piece for the 6 port actuators. and as far as the dual exhaust deal why dont you just order the y pipe and mufflers???

 

Because I can buy all the piping already bent and 2 good quality mufflers for less than $150. Or maybe do just one muffler and the presilencer then do the dual exhaust and have tips out each side. I will probably get the racing beat presilencer though since it keeps the 5th and 6 ports working.

 

Mazdatrix offers a header that has an O2 bung and 6port actuation added in.
Yes, you will want an 02 sensor if you intend to keep EFI in any form.

WAM.. you have a turbo minivan with all that stuff on it? That's nuckin futs.

 

You could also use your air pump to activate the ports.

 

as for the bends, a couple of45's or 90's should do it. you can always chop and weld portions of them to give you your desired angle, but it is pretty tricky to get it to look good. as for the Y pipe, you could use two 45's, probabily trimmed to around 30 or so, and join them together (after a really tough cut) so they match into the mid pipe/cat/what have you. Good luck man!

 

i agree, use my air pump to activate my 5th and 6th ports and i works flawlessly for about 4 months now

 

Not all of that stuff is installed yet but I have most of it plus 4 additional injectors, nitrous express, a 60-1 hybrid turbo, other gauges, 2 step boost control, ignition amplifier, and more, the goal is to get mid 11's by the end of this summer, all for under $3000 easily.