V8V 4.3 Power Upgrade kit - Is it worth it? Can parts be sourced for less the dealer?
 

I was curious how many have this and think it makes a noticeable difference to the car.

Would you do this upgrade before adding a high performance exhaust and 200 cell cats?

Which is the better bang for the the buck? Also I haven't seen any HP or TQ maps for the 4.3 power kit, are you gaining power all over the rev range or is this just a top end gain?

I have the Power Pack on my 4.3L and it's pretty expensive. I *think* it was in the neighborhood of $5k installed. You get 20 hp and 9 tq, which the car definitely needs. The Power Pack changes out the air boxes to ones with extra flaps that open at 4500 RPM, so the most obvious difference in power should be above that point.

I also have high-flow cats and a rear muffler. The cats make a nice difference (a bit of power and a beautiful noise) and are probably the best bang for your buck. The muffler doesn't add too much, but it is lighter than stock and gives a nice exhaust note.

The Power Pack is supposed to bump the 4.3L from 380 to 400 hp. I've had mine dyno'd with the Power Pack, cats, and rear muffler at 343 whp. On that dyno, I should be at 410-15 bhp.

The cats/muffler are on the exhaust side, the Power Pack is on the intake side. They do work well together, so if you can stomach it, I'd recommend doing both. Stuart also has a tune, which I'm planning to get soon.

Great info, thank you.

Now..does this bring the performance, throttle response and driving experience up about even with the 4.7 (numbers you mention are close)? How would you compare a 4.3 Power Kit + Cats + Exhaust equip car to a 4.7 V8V?

On the high end it helps a lot, but down low you'll notice the lack of torque compared to a 4.7L. I drove a V8VS then got back into my 4.3L (with the mods listed above). I could tell immediately that the torque wasn't there. But that's mainly in the low rev range. Once the engine is up and spinning, it's a great ride. I'm hoping the VelocityAP tune from Stuart helps with that low-end. That's where the 4.3L struggles. Between a better tune and sharper throttle response, I think the tune will help.

We can do a VelocityAP 'Power Pack' consisting of Manifolds, Cats, Filters + Tune which will get you more than double what the AM Power Kit does, and for roughly the same money. Plus it will sound really racy :)

Just want to clarify something... When I said you can tell the lack of torque, it was in reference to my driving the 4.7L and my modded 4.3L back-to-back. Any other day of the week, my car doesn't feel lacking.

Was a similar Power Kit offered by Aston for the 4.7? I have noticed a combination of 4.7 intake manifolds colored both silver and black...

If I remember correctly, the V8VS has the black intake manifold. The setup on the V8VS is the same as the Power Pack - the modified intake manifold and different airboxes. The Power Pack also has a black intake manifold, also modified for the new airboxes. Any Vantage with normal airboxes (the ones without the extra flaps) should have a grey intake manifold, unless it was painted (non-original). So:

Grey intake manifold: standard manifold, standard airboxes, etc.
Black intake manifold: modified manifold, airboxes with extra flaps - either the V8VS or the Power Pack.

I have AM power upgrade and high flow cats on a 4.3 and other than torque, it is comparable to a 4.7. I would consider headers the remaining mod. A stock 4.3 feels noticeably different. The additional torque is just enough to enable pulling away from a stop applying no throttle, greatly extending clutch life.

Headers are where the substantial power gain is on these cars, right? Does the engine require removal for fitment of new headers?

I am also curious what other engine setup tweaks the V8V GT4 Challenge cars have...both older 4.3 and newer 4.7 have from a motor standpoint. Anyone know or race one?

Headers are one of the big areas for sure, as well as high flow cats. The engine doesn't need to come out.

The GT4 cars already run 200 cell motorsport cats + air filters, and have a more free flowing and lighter silencer assembly.

The new Vantage GT comes with the black manifold, airbox flaps and even the Sport exhaust included. Can you tell I have the bug for a new car? :)

Does the Velocity power pack pass California Smog?
 

My biggest concern and reason for not doing some of the mentioned mods to a 4.3 is the ability to pass California smog inspection, which at this point I need to do every 2 years. Have you had experience with that Stuart?

I have had customers pass California Emissions testing with these mods, no reported failures to date. Technically, the cats are not CARB approved so shouldn't pass but I don't think they look for the approval notice, just sniff it and pass it. If worst came to worst you could always swap the cats out for the originals. Kind of a pain but only an hour or so to put them in and the same to take them out, and if it is only every couple of years...

Hypothetically, you could swap the OEM cats back on before the inspection then swap the 200-cell cats back after.