Diverter Valve Necessary for Tune?

[SBD_Dauntless]

I'm getting ready to tune my Fiesta with a flash tune from Dizzy for both 93 octane and E30. I have all the parts that I need except for a DV, which I'm undecided on. From what I understand, an upgraded DV would help with consistent boost levels, especially with a tune. I have no experience with tuning though, so I don't know how exaggerated any of these claims are. Is a DV necessary to have for a tune, or even that helpful? I just want to be sure I'm not wasting money on unnecessary upgrades, especially when an AP, spark plugs, the tune, smoke testing, and tools are already getting quite expensive.

 

[HBEcoBeaST]

Necessary? No. I ran the same E30 tune with OEM bypass valve for almost a year before upgrading to a used gfbv+. OEM held up fine. There's a difference in how the gfbv+ holds boost better when shifting or making smaller throttle adjustments but nothing major. I run an ITG/whoosh hose intake (loud) and it didn't make any noise difference there. As long as you get the correct tune for your fuel and parts you'll be good [emoji1303][emoji573][emoji1531][emoji267]

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[HBEcoBeaST]

I'm getting ready to tune my Fiesta with a flash tune from Dizzy for both 93 octane and E30. I have all the parts that I need except for a DV, which I'm undecided on. From what I understand, an upgraded DV would help with consistent boost levels, especially with a tune. I have no experience with tuning though, so I don't know how exaggerated any of these claims are. Is a DV necessary to have for a tune, or even that helpful? I just want to be sure I'm not wasting money on unnecessary upgrades, especially when an AP, spark plugs, the tune, smoke testing, and tools are already getting quite expensive.

Smoke testing? I don't understand.

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[SBD_Dauntless]

Smoke testing? I don't understand.

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Boost leak testing. I think one of the methods uses smoke to find any leaks? That may not be the correct terminology but I meant testing for boost leaks. The pre-tune checklist on the Dizzy website recommends checking for any leaks prior to tuning. I doubt I have any as I'm seeing 21 psi at peak and -10 psi at idle, but it doesn't hurt to check.

 

[Clint Beastwood]

The upgraded DV's are for two purposes:
1. Your current one is bad/leaking.
2. General "Quality of life" improvement. Doesn't make the car faster, doesn't improve mileage, doesn't have any measurable impact on the performance of the car vs. the stock DV. It does, however, make part-throttle a little more comfortable, off throttle/on throttle transitions more comfortable, and depending on what you get and your intake setup, can sound kinda fun.

I've used GFB DV+ for years - with the FiST I went with the Turbosmart EM, and was glad I did. It doesn't have to be lubed, it's rebuildable, and it makes neat sounds. You'd be fine with either, I just got tired of cleaning/lubing the GFB on previous cars. Some people are fine never lubing it, others have to do it every 10k miles. With where the FiST one is located, I didn't want to do it often, so I went Turbosmart and am very happy with it. The GFB DV+, by design, gets its lubrication from "blow-by", so if you have a catch can, it might wind up running dry and need additional lubrication occasionally.