Same with mine - But I was told by my tuner to allow the tip to be open - it works off of atmospheric pressure - 
Turbo c5
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From: smackover arkansas
Turbo c5
I have a 98 c5 with a single turbo and a speed density tune I just built a new boost pipe just wanted to know if it was necessery to hook up the vacuum line to the regulator or can i cap it off its all factory fuel lines and regulator .
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From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
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Ummmm.......I wouldn't leave that open or capped. I converted to a 98 style system on my 99 and that vac line is the vac reference for the regulator. If it's open then you're ONLY getting fueling as if at 0 MAP, I.E. in a N/A setting WOT. Unless your tuner has tuned for it, you're overfueling at part throttle conditions when that 0 MAP pressure isn't needed. I can DEFINITIVELY attest that the regulator is referenced for boost too though as my fuel pressure comes up 1:1 with boost. Hook that vac line back into the manifold and leave it be.
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From: West Norriton PA
St. Jude Donor '08
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Instructor
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From: smackover arkansas
Turbo c5
I like it except I haven't figured out a air filter system yet but to answer your question about the power I should know in 2 weeks I'm going to Dallas performance to finish tuning I'll let you know.
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From: West Norriton PA
St. Jude Donor '08
My only issues is with the the turbo hitting my MCM carbon hood and Katech valve covers.
Was thinking about reversing my radiator and then droping the turbo down a bit and out front to clear the valve covers and hood.
Post up your results and some pictures.
Thanks
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From: smackover arkansas
Turbo c5
Yeah I had a major problem when I went to shut my hood I had a76mm precision and the compressor housing was hitting so I had to buy turbonetics 76 because the housings are a little smaller your probaly right your going to have to drop the turbo down which isn't really a big deal Another problem was tha crossover Brian built it off a z06 my car is a auto so the trans lines hit that's why I built everthing except for tha header
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From: West Norriton PA
St. Jude Donor '08
Yeah, the prototype was his red Z06 that he built it on. I had posted some pictures along time ago. Thanks for saying something about the cross-over pipe because I have a scattershiled (quicktime) in my Z06 and I'll bet the cross-over pipe ain't going to clear it.
