Lots of negative experiences with them on the forums, however I ran an APS dual port for years without a remap and it was fine, however the APS doesn't vta unless at full boost and even then it was only a very small vent. The vta became much greater once on a stage 1 and mapped to 275.
Remember that the MAF measures the air coming into the engine at the air box so any 'dumping' of air after this will affect the mixture causing the engine to run rich for the period where the air is less than metered, this is not normally as bad as lean running but can cause problems. Most cases of poor running however (especially at idle) are due to poor quality valves that leak, any good valve should be closed at idle therefore no difference in running.
I now run a Forge VTA valve however I am MAFless so the mixture is not affected, I will be switching to D/V less soon as the constant flutter/whooshing is getting annoying!
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2005 Spec B 6MT - KiDO tuned (~270Bhp)
Custom exhaust - Cosworth filter - Samco Intake - Tints - Bilstein B8/B6 & STI springs - SuperPro ALK - Whiteline positive shift kit, rack mounts, rear adjustable camber bushes, front ARB mounts & strut brace, 20mm rear ARB with AVO mounts, - Hardrace Gearbox and pitch mounts - Prodrive PFF7's - Front Brembos - Kenwood CarPlay - 1/2 carbon grille - STI front splitter
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