Is this a bad design on HKS's part?

I assume this DP will give wastegate chatter but I thought that wastegate chatter was a very bad thing or am I wrong?

Would a bell mouth design DP be a better safer option than the HKS DP?

Have a read.....

HKS Wrx/Sti Downpipe, 2002-6 Subaru WRX/STi, WRX downpipe from JSC Speed

 

think you need to search turbo stall by the sound ov wot your saying thats wot you mean

 

stupid design if U ask me.
first created a big restriction at the turbo exit and then use a big 3" pipe.
just stupid.
buy a H&S

 

YOu don't want 'wastegate chatter' - there's no such thing IMHO - it's a completely made-up techy sounding phrase. What you are thinking of is 'a funny noise that is heard from some turbocharged cars when you let off, that doesn't quite sound like a dump valve dumping'. It is called compressor stall and is literally the sound of the compressor wheel being forced to slow down because boost has backed up against a closed throttle plate. Under normal circumstances, the standard recirculating DV opens, releases this trapped boost so that it goes back round to the inlet side of the turbo and everything is fine and dandy. You might hear a slight whoosh or chuff as this happens when changing gear or letting off suddenly.

If you want compressor stall there are a number of options, but in general the further you take your system away from standard the more noisy and weird sounding it will be. Something like an atmospheric DV with an induction cone on the inlet, lightly let off the throttle so it doesn't dump out fully; that should be the sound you're after.

The downpipe is nothing to do with it. And that downpipe in particular looks like an absolutely shocking design. You are right to wonder why the wastegate part would be plated over. It's stupid. For best flow the wastegate and turbine outlet both need to flow in the same direction. By plating over the wastegate side, you are guaranteeing that the two flows are at right angles to each other. You'd be pushed to design a worse exhaust than that.