cat-back piping

[rollbonez]

ok, so for all you guys with 99-03 GTs who had your piping redone, did you guys route the new piping over or under the rear frame's cross bar.

I went to get another quote today on new 2.5" piping from the cat back and the guy said the stock GT piping that is bent over the rear axle is the most retarded thing he has ever seen.

I felt the pipe and it was nearly pressed into a flat oval to get around that bend.

Still, the best quote I got to have press-bent 2.5" piping put in was $125 US. Guess I'll live with it for now....

[rollbonez]

Oh! Also, does anyone think going to 2.5" is going to relieve too much backpressure?

My intake setup is just the stock Ram Air setup with the filterbox top removed and a 7" K&N cone sitting inside the bottom of the filterbox sucking in the fresh, cool air from the ram air.

I currently have the stock piping with a Magnaflow on the back. It has relieved some backpressure without much loss on the low end, but the difference in hp is barely noticeable.

I just think that the stock piping is amazingly restrictive.

I am going to fabricate a custom heatshield from with high-density foam from an upholstery shop to keep the heat soak to a minimum.

Thoughts on any of this?

[Pte Socks]

have you looked at mendrel bent piping? im still trying to find a shop around here that does that.. but ive heard its teh best thing to go for if you dont want restictive piping..

[rollbonez]

Originally posted by Unrealoaded
have you looked at mendrel bent piping? im still trying to find a shop around here that does that.. but ive heard its teh best thing to go for if you dont want restictive piping..

I have gotten some quotes on it and it was ridiculously expensive. Because of my warranty, I can't do any major intake work outside of a CAI or cone filter for the next two years, so I don't need to open up huge amounts of flow on the backend.

I am just looking to go 1/4" bigger with 2.5" pressure bent piping.

ANYTHING's got to be a hell of a lot less restrictive than the stock piping.

[VanishingImage]

i don't see why it is....its high here too....If they are an exhaust place they should have the right machines and shouldn't charge so much.

[Greed4Speed]

Its because they have to buy pre-bent curves. They probably won't have a mandrel machine, and if they do they gotta pay for it. They aren't cheap. Just get pressure bend. So you'll have a little less flow. That may equate to a 2 hp loss over mandrel bend.

Think about it, mandrel systems are basically a 10 hp gain. An after market muffler w/ stick exhaust is about a 5 hp gain. Running a larger diameter pipe w/ pressure bend will net about another 2-3 hp. Is the cost of a mandrel system worth the extra $200 for 2-3 hp over pressure bend?

I ran a 12.90 in street trim in my 70 Camro w/ a pressure bent system. Cars before mandrel bend was the trend ran fast w/ pressure bend exhausts. Ya it'll increase airflow but in a dollar/Hp view is it really worth it? I say no.

[Themeneea]

is pressure bent stock piping?

[Pte Socks]

i dont think so themeneea. I get that conclusion from teh fact that a performance muffler gives you aoubt 5 whp while with new piping you get an additional 2-3 whp. The only way that could be so is that pressure bent is better than stock piping

[Pte Socks]

i got one question though.. is there something like straigh back piping? What i mean is piping that only has like one bend to go into the muffle but besides that just goes straight back from the cat to the muffler. I wonder if you can do that on our cars. Any help?

[Pte Socks]

Cool... i just found a place in town that does mandrel bent piping.. 60$CDn a bend.. so it aint that bad

[ferran586]

Originally posted by Unrealoaded
Cool... i just found a place in town that does mandrel bent piping.. 60$CDn a bend.. so it aint that bad

But how many bends are in your exhaust system? Hopefully not too many. :)

[Greed4Speed]

There are all sorts of bends in the exhaust system. Climb underneath and look. If you really want mandrel, just get the mandrel bend over the rear and if you're going w/a trasverse muffler the bend into the muffler & both bends out. Still thats $240 cdn. It is worth an extra couple of HP? You can skip the bend over the rear and just run the exhaust under the middle. I've seen that done, but if you do that might as well go crush bend.

The stock system is pressure or crush bend. Stock piping size is 2" on SE and 2.25" on GT. I don't think 2.5" will be bad. I saw a dyno pull on a 3.8L Camaro w/ 3" piping that increased torque and HP, so 2.5 should be fine. If the 4cyl imports see improvements w/ that size, the 3400 will too. Just don't expect a huge diff between 2.25 and 2.5.

[1995grandam]

here in enid we dont have any shops that mandrel bend pipe, and i found out why. a guy at ramco told me a mandrel bending machine costs from 250-300 thousand dollars.... kinda extreme.

oh, and i have 2.5" piping on mine, and i feel no loss in low end torque, and maybe some gain. and the top end horsepower gain is amazing.

[Pte Socks]

ive heard taht the se and gt both have 2.25" piping.. and i think i will be staying with that.. As for the price.. well there is 5 or 6 bends ive counted.. now i dont think i will get them all bent.. but i will be getting several done.. Im expecting to pay around 800$ for this exhaust.. half of it to my borla muffler and tips.. and the rest to my piping.. i sitll have to go to this place and check it out

[sound_xtreme]

yea, pretty sure stock is 2.25 mandrel bent.

[Themeneea]

ive heard taht the se and gt both have 2.25" piping.. and i think i will be staying with that.. As for the price.. well there is 5 or 6 bends ive counted.. now i dont think i will get them all bent.. but i will be getting several done.. Im expecting to pay around 800$ for this exhaust.. half of it to my borla muffler and tips.. and the rest to my piping.. i sitll have to go to this place and check it out

is that with or without tax

[rollbonez]

Originally posted by sound_xtreme
yea, pretty sure stock is 2.25 mandrel bent.

There is no way that all the stock piping is mandrel bent. There's a section of piping that is definitely crush bent towards the back of the vehicle on all the 99-03 GTs.

It is the section of pipe that rises over and around the rear axle and frame and then drops down to the muffler. If you get under the car and feel the top of that pipe, it is nearly flat on top of the pipe.

[sound_xtreme]

looks mandrel on mine. when pipes are crush bent they always have ripples on the inside of the curve.

[Pte Socks]

well boys and girls for my car at least.. im redoing all the piping all the way from the cat back to my tips. As for size.. im sticking with the 2.25 and ill be getting mandrel bent piping on it all. I know this is going to cost a fortune but it will kick so much ass and im sure i will love it. Hp and torque doesnt come cheap.. that i truly do know