silverarrow89 Posted September 4, 2008 Report Share Posted September 4, 2008 About to pick up a 2.5" DP to 3" flex to 3" highflow cat to 3" single in/dual 2.5" out exhaust system that Wicked had for sale here in NJ. Looks good, nice deal, picking up in a few weeks...cool guy, but wondering when I should put this on? Will it work with a factory 12a or should I wait for when I upgrade to a 16g or 17c? I have other stuff to do before I add the bigger turbo in the spring like radiator/IC/stressed EM/boost controller/balance shaft elim/89 ECU/etc, no rush. My real question is, will performance be hindered with a lack of back pressure from going to an over, over sized exhaust - from 2" to 3"? I've read on the TEP site that a 3" may be or is overkill and will not produce enough back pressure at lower RPM. Also read this http://www.starquestclub.com/forum/index.p...urbo+back\, noting Shaggy's comment. Some real world views appreciated. Link to comment Share on other sites More sharing options...
Richie_Rich Posted September 4, 2008 Report Share Posted September 4, 2008 I've got a full 3" exhaust on my car no cats and it works great. A little loud, but it doesn't bother me. Link to comment Share on other sites More sharing options...
silkdagger05 Posted September 4, 2008 Report Share Posted September 4, 2008 (edited) what a tuner shop told me. 1. 2.5 is good for 300 hp or so. 2. A cat(I have a low flo since I need it for em, but a high flo should be good for it ^^)is great with a smaller turbo to help with back pressure so it spools slightly faster ( around 300 rpms quicker) 3. to loud mean people will notice ( whether you want them to or not) so theft and or letting the other guy know how bad your ride is be4 you want them to know. tickets ect. 4. 3" should get a bigger turbo than a 12a ...maybe even bigger than a 14g ? (not sure there) 5, they both sound so nice ^^ lol the guy is a friend and had a starion so i took his word. tho the DP helps a ton. nice sound but makes it slightly rich due to no first cat. my car is good so far and has 0.06 ( or 0.6) on smog. hope i helped a little as this site has bin so nice to me ~Tony p.s would dual lower back pressure enough to effect the turbo ????? Edited September 4, 2008 by silkdagger05 Link to comment Share on other sites More sharing options...
Lusion972 Posted September 4, 2008 Report Share Posted September 4, 2008 Put it on, it wont hurt you... Link to comment Share on other sites More sharing options...
silverarrow89 Posted September 4, 2008 Author Report Share Posted September 4, 2008 p.s would dual lower back pressure enough to effect the turbo ????? I doubt the duals alone would do it, as the input is still 3" Put it on, it wont hurt you... Thanks Lusion, I like that answer :dancing: I pick it up in about 2 weeks and will take pics of the install. Link to comment Share on other sites More sharing options...
jahjah Posted September 4, 2008 Report Share Posted September 4, 2008 The bigger and more freely flowing the exhaust the quicker your turbo is going to spool. You are also going to lose out of boost power. Which is why i went with a 2.5" turbo back with no cats or resonators and a straight through muffler. Link to comment Share on other sites More sharing options...
Lusion972 Posted September 4, 2008 Report Share Posted September 4, 2008 In the future you may want to upgrade to a 3" DP if you upgrade your turbo. 3" is a bit much when you have a smaller turbo and honeslty 3" is over kill with most turbos because you lose alot of your lower end power. Back pressure is needed for that off the line power until your turbo spools up. I will always use 2.5" just because I dont see the need for anything larger. Link to comment Share on other sites More sharing options...
Scotty Dont Posted September 4, 2008 Report Share Posted September 4, 2008 3" is over kill with most turbos because you lose alot of your lower end power. That what a two step rev limiter is for :biggrinumbrella1: Link to comment Share on other sites More sharing options...
silverarrow89 Posted September 4, 2008 Author Report Share Posted September 4, 2008 I just don't want to put the new exhaust on my "standard" car and it cause a lag or produce less power than the stock 2" diameter. Once I do the 16g or 17c in the Spring, the 3" should be worth it, I just don't want to to be puttering around till then. I should mention that the exhaust the previous owner had on the car leaves a lot to be desired as far as looks and performance, but that's a different story. Link to comment Share on other sites More sharing options...
strang3majik Posted September 4, 2008 Report Share Posted September 4, 2008 (edited) i have 2 1/2" dp into 3" pipe, gutted cat and a flowmaster on the stock 12a...and it runs good...no issues, Im sure a bigger turbo would take the better advantage of it though. Edited September 4, 2008 by strang3majik Link to comment Share on other sites More sharing options...
silverarrow89 Posted September 4, 2008 Author Report Share Posted September 4, 2008 (edited) i have 2 1/2" dp into 3" pipe, gutted cat and a flowmaster on the stock 12a...and it runs good...no issues, Im sure a bigger turbo would take the better advantage of it though. There's my answer, I can throw it on when I get it. THANKS majik! PS. I want to make your signature (right side) into a sticker for my engine bay, would you mind? if ok do you have it in a larger higher res image, I'll need to change it to Mitsubishi Starion. (NOT THAT'S THERE IS ANYTHING WRONG WITH THE IMAGE ON THE LEFT SIDE OF OUR SIG) PPS. I'll make you one if you want. Edited September 4, 2008 by silverarrow89 Link to comment Share on other sites More sharing options...
lancea9847 Posted September 4, 2008 Report Share Posted September 4, 2008 (edited) There's my answer, I can throw it on when I get it. THANKS majik! PS. I want to make your signature (right side) into a sticker for my engine bay, would you mind? if ok do you have it in a larger higher res image, I'll need to change it to Mitsubishi Starion. (NOT THAT'S THERE IS ANYTHING WRONG WITH THE IMAGE ON THE LEFT SIDE OF OUR SIG) PPS. I'll make you one if you want. can you make me one? just change it to STARION and also change 200+RWHP to 300+RWHP HP :eek1bluegreen: thankx Edited September 4, 2008 by lancea9847 Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted September 4, 2008 Report Share Posted September 4, 2008 I wouldn't worry about it honestly. Think about the amount of backpressure a N/A engine makes with nicely flowing headers and exhaust. Now think about how much backpressure is created by blocking the exhaust flow with a turbine. I have a 3" on my mildly modded SQ with the 12a. I thought it was great. I didn't notice any drop in low end what-so-ever. Now I run a s16g though, and notice no real increase in spooling time. My upgrade plans surpassed 350rwhp or so, thus why I chose the 3" from the get go. For the record, people with 2JZ's usually only upgrade the 3" exhaust to a 4" after 700rwhp. They just don't see gains before that. "Lag" is severely overrated, people put way too much stock into that word. Drive or ride in a car that takes two to three seconds before the turbo really comes on, and the last thing you're thinking about while fighting for traction at 70mph is how long it took the turbo to "come on". Especially when the word "explosive" still doesn't quite grasp the feeling of what happens when boost comes on. Add into that what Scotty mentioned with the two-step launch control, or cars like both of mine(automatics) that can launch with 10psi by loading the motor up against the brakes. Link to comment Share on other sites More sharing options...
shift1313 Posted September 4, 2008 Report Share Posted September 4, 2008 (edited) typically you want 10% larger down pipe than the outlet of your turbo. for a 12a this is 2.5" Its not really back pressure we are concerned with its exhaust velocity. If you run too large of a down pipe your turbo will spool quickly but going from 2" to 3" you will get a large drop in velocity so this will "stack up" as the revs get higher. You really cant say that 2.5" is good for x hp. it all has to do with flow. velocity and heat. If your exhaust cools too quick it will slow down and "stack up" again causing the same issues. this is why you see people wrap the headers and down pipes. its not to keep heat away from the engine bay(partially is) but its to keep the heat in the exhaust so that it can flow as fast as possible. just like a header, long tube that are optimally sized will give you great velocity into the turbine. the question at hand will it hurt you. Going from a stock exhaust you can only get better:) Will you be able to optimize your exhaust, no probably not. 2.5" all the way back is enough to support a good amount of power. every time you transition from 2.5 to 3" your exhaust is slowing down, the farther from the engine, the colder it gets, the slower it gets. All this doesnt really matter unless you are trying to squeeze everything out of your car. You will be happy with the exhaust, go for it. if nothing else the sound will make you think its faster Edited September 4, 2008 by shift1313 Link to comment Share on other sites More sharing options...
silverarrow89 Posted September 4, 2008 Author Report Share Posted September 4, 2008 (edited) ... if nothing else the sound will make you think its faster LOL I have a 3" on my mildly modded SQ with the 12a. I thought it was great. I didn't notice any drop in low end what-so-ever. Now I run a s16g though, and notice no real increase in spooling time. I'll be installing mine when I get it, will be good to go. can you make me one? just change it to STARION and also change 200+RWHP to 300+RWHP HP :eek1bluegreen: thankx no prob Edited September 4, 2008 by silverarrow89 Link to comment Share on other sites More sharing options...
Komeuppance Posted September 5, 2008 Report Share Posted September 5, 2008 If you're planning to get an exhaust, and want a quality piece... take it to an exhaust shop. It will cost much less and fit better than the premade systems you can buy at this point in time. BTW, if your car is lowered... watch out with a 3" exhaust... haha... -Robert Link to comment Share on other sites More sharing options...
silverarrow89 Posted September 5, 2008 Author Report Share Posted September 5, 2008 If you're planning to get an exhaust, and want a quality piece... take it to an exhaust shop. It will cost much less and fit better than the premade systems you can buy at this point in time. BTW, if your car is lowered... watch out with a 3" exhaust... haha... -Robert Thanks Robert. This was custom made by a guy Wicked knows, looks tight. I'm going to rebuild the suspension just shy of lowering, so I'm ok there, you're right though, i would have been screwed, I never thought about the larger diameter having ground clearance problem. Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted September 5, 2008 Report Share Posted September 5, 2008 (edited) Robert is exactly right. I'm lowered a good bit over stock, and not only is the extra diameter of the 3" a problem, but the setups we have available to us aren't tucked up close to the body at all. Edited September 5, 2008 by JustPaus_88TSi Link to comment Share on other sites More sharing options...
strang3majik Posted September 5, 2008 Report Share Posted September 5, 2008 There's my answer, I can throw it on when I get it. THANKS majik! PS. I want to make your signature (right side) into a sticker for my engine bay, would you mind? if ok do you have it in a larger higher res image, I'll need to change it to Mitsubishi Starion. (NOT THAT'S THERE IS ANYTHING WRONG WITH THE IMAGE ON THE LEFT SIDE OF OUR SIG) PPS. I'll make you one if you want. lol...no problem...sounds good too. I love that these cars sound like they got something to them...not like the wet farts hondas throw out. and will PM you about that. Link to comment Share on other sites More sharing options...
Shelby Posted September 5, 2008 Report Share Posted September 5, 2008 turbo exh systems get a lot hoter then na exhs do,, not sure a nice close to floor pan exh is a good idea Link to comment Share on other sites More sharing options...
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