ive been readin alot over the past couple weeks about the upipes for the wrx from these two companies, the helix one has a flex joint and is has a bigger diameter 2.25", the hks up pipe has no flex joint and the diameter is 45mm (about 1.77") which is obviously closer to the stock diameter, both are catless.... i am running the hks up pipe now but was thinking, wouldnt an uppipe with a bigger diameter be more beneficial?? i was reading about the perrin uppipe on their website, and THEIR up pipe also has no flex joint but has an inside diameter of 1.62", theyre reasoning: "The proper inside diameter of 1.62 inches is critical. Pre-turbo exhaust velocity is critical to boost response. Improperly oversized header and up-pipe systems lower exhaust velocities slowing spool up for larger turbo's decreasing power and increasing boost lag. "

so which uppipe is the best for my situation?? im runnin a helix downpipe, and hks uppipe and carbon ti exhaust, and vishnu's stage 1 on their xede...dont worry im gonna buy an AP as soon as gruppe-s gets some in... so according to perrin my hks uppipe is too big?! im gonna get a vf34 upgrade as soon as i get my car smogged for registration in 4months, would it help to buy the helix up pipe?

im suprsised i couldnt find a topic covering all these up pipes and diameters before, if someone could help me figure this out or has a link that'd be great

thanks
-shiraz

 

you could always just gut your stock uppipe if you want to stay the same diameter

 

I'd go with an STi, bosal or gut the stocker.

 

+1 I agree.

 

uhhhh so youre sayin take off my hks and put on an sti uppipe!!?! whaaa!! its not that i WANT to stay stock diameter, im just wondering is that more beneficial, im runnin the hks right now and thats bigger than stock, but the helix is uber bigger, so i was wondering if helix is the better uppipe

im sorry if i was unclear, my question is which is the most power beneficial up pipe on the market, SOMEBODY out there has to have done some research on the different diameters and their relationship to horse power, bah ill just pm gruppe-s i guess

 

i got a helix and i love it

 

you posted your own answer....I 100% agree with what Perrin states. A proper sized uppipe is much better than a larger one.

Keep the HKS.



If you are looking for more power a list of current performance mods would be nice...

 

ideally, you'd want the smallest diameter uppipe possible for faster spoolup times. A non-flex uppipe would technically be "better" over a flex uppipe in the sense that you want the least resistance and minimize disruption of exhaust flow.

But even then, there are minimal differences in terms of performance, as gruppe-s or whoever u pm will undoubtly tell u about the hks vs helix uppipe. But imo, going with a smaller diameter uppipe is better.

For this reason, it's pointless to switch to another uppipe (i.e the perrin one you're thinking about) since u already have the hks uppipe, which is pretty small in diameter as it is. You'll just be wasting money for little to no performance gain between switching aftermarket uppipes.


no because a bigger uppipe diameter will increase your turbo lag and u will have slower spoolup times.

It's not an uppipe related issue, but if u want to see how going bigger will affect your spoolup and lag, try buying a bigger aftermarket tmic and put it on your stock turbo wrx and see what it does to your spoolup times

 

thanks guys