Hello.

As title, only modifications are dump valve, magnecore leads and magnex back box, was told it's a must for any Subaru but researching myself suggests it might overfuel, if so what problems will this cause?

Thanks in advance!!!

 

Firstly, why did you replace the OE dumpvalve? It does a good job and doesn't allow overfuelling, which a VTA one will. This can cause borewash and wreck any cats in place

Secondly, depending on the AGE of the car and it's mileage, you might gain from fitting a new fuel pump, the old one gets tired

Thirdly, it can't overfuel unless you mess about with the fuel pressure regulator. So don't, and you'll be OK

And fourthly, you OUGHT not to need a map tweak, but speak to any REPUTABLE seller: Harvey Smith, Stu on here, Mark At Lateral, David at API, Allan Jeffery at Engine Tuner, and they will advise.

 

The modifications were already on the car, I am not mechanically minded so am a noob really, I won't be messing around with anything else, it's done 121k so was told it was a good part to replace? As for the dump valve how does it cause overfueling?

 

Mate, do a search on here and you'll find that anyone will tell you that the only reason to fit a dump valve to a scoob is to attract attention and sound like a boy racer!
The sensors on your car will be calibrated to expect a certain amount of air back into the intake - standard scoobs are fitted with a recirc valve.
Changing this to a VTA version can, I think affect the amount of fuel the ECU thinks it needs to feed the engine hence the over-fuelling concern - sure alcazar will probably correct me if I've got that wrong .
Best thing you can do is fit an OEM recirc valve to the car - most owners report the cars run 100% better as soon as they remove a VTA valve.

You may also want to check that your car's not also running a cone filter in the engine bay, where the filter will suffer heat soak and you'll suffer power loss.
Unless the car's heavily modified the standard airbox and a good panel filter is good for at least 300bhp, so if you've got that - best thing to do would be to replace it with an OEM item again.

As for the fuel pump, I believe if you replace it you may need a map tweak unless you replace it like for like.
My car's done 80,000 miles and I replaced mine when car had its recent re-map with JGM.

 

As said change the dump valve back to standard it will run better. Also the fuel pump on a classic may be tired and while uprated one isnt required its a preventative measure for failure.

2 YEAR WARRANTY ON THE HRC PUMPS, unlike 12 months with walbro.
Also made by DENSO so top qaulity also

http://www.j-autos.com/hrc-performance.php

 

It did have a hks mushroom filter but I was fold to bin that so running a oe airbox/filter, only had the car 6 weeks now and had a exhaust valve failure in cylinder number 4, a low mileage unit has been fitted now, around 60k. The cause of the valve failure was never pinpointed so keeping her as standard as possible, advice was walbro is to stop running lean and avoid possible failures. I think I have the oe dump valve so might be worth a fit to see if there is a difference!!!

 

That denso unit doesn't look bad, good price too.